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THE      PHYSICAL     GEOGRAPHY 

GEOLOGY,   MINERALOGY 

AND   PALEONTOLOGY 

OF 

ESSEX  COUNTY,  MASSACHUSETTS 


JOHN    HENRY    SEARS 

Curator  of  Geology,  Mineralogy,  and  Botany 

AT    THE    PeABODY    MUSEUM, 

Salem,  Mass. 


SALEM,   MASS. 

PUBLISHED  BY  THE  ESSEX  INSTITUTE 

i9°5 


QE 
S4 


Copyright,  1905,  by 
THE   ESSEX  INSTITUTE. 


bos™  COLLEGE 


,   COMPLXMENTS   OF 

JOHN    H.   SEARS 


GEOLOGY    AND     BOTANT 

PEABODY    MUSEUM. 

SALEM,    MASSACHUSETTS. 


TO 

DAVID    PINGREE 

THIS  VOLUME  IS  DEDICATED  IN 

APPRECIATION  OF  HIS  UNFLAGGING  INTEREST 

AND  GENEROUS  ASSISTANCE 


PREFACE 


Twelve  years  ago,  at  the  request  of  the  Trustees  of  the  Peabody  Acad- 
emy of  Science,  I  began  work  upon  a  preliminary  map  of  the  bed-rock  of 
Essex  County,  which  was  published  in  1894  in  the  Bulletin  of  the  Essex 
Institute.  In  the  meantime  I  prepared  a  number  of  short  papers  which 
were  also  published  in  the  Bulletin,  under  the  general  title  of  "Geological 
and  Mineralogical  Notes."  Since  1894,  the  work  of  mapping  the  out- 
crops of  bed-rock  in  the  County  has  been  continued  and  the  superficial 
deposits  of  sand,  gravel,  till,  clay-beds,  peat-deposits  and  silts  have  been 
plotted  with  the  greatest  possible  accuracy.  With  the  exception  of  such 
areas  as  are  under  water,  every  sixth  of  a  mile  in  the  entire  County  has  been 
examined  several  times  by  ranges  running  from  east  to  west  and  also 
from  north  to  south.  In  the  determination  of  the  rocks,  over  eight  hun- 
dred thin  sections  have  been  prepared,  the  larger  portion  of  which  are 
preserved,  together  with  the  rock  specimens,  in  the  cabinets  of  the 
Peabody  Museum.  The  results  of  this  close  examination  of  the  surface 
are  presented  in  the  following  pages.  The  physical  geography  of  the 
County  is  described  and  much  space  has  been  devoted  to  the  surface 
features.  The  outcrops  of  bed-rock  are  superficially  described  in  the 
text,  and  at  the  end  of  the  volume  a  map  will  be  found  on  which  the  de- 
posits of  boulder-till,  gravel-terraces,  sand-plains  and  other  features  are 
represented  together  with  all  outcrops  of  bed-rock.  The  points  of  the 
compass  indicated  are  according  to  the  magnetic  compass,  its  variation 
from  the  true  north  in  this  region  in  1898  being  12°  7'  west. 

To  Dr.  Henry  S.  Washington,  of  Locust,  New  Jersey,  I  am  indebted 
for  chemical  analyses  of  many  of  the  rocks,  especially  those  in  the  syenite 
group.  I  also  would  acknowledge  my  obligations  to  Dr.  William  H.  Dall, 
of  the  United  States  Geological  Survey,  for  assistance  in  determining  the 

5 


6  PREFACE 

leda  marine  clay  fossils;  to  Prof.  A.  E.  Verrill,  of  New  Haven,  Conn.,  for 
identifying  the  starfish  found  in  the  marine  clay  at  Lynn;  to  Mr.  J.  A. 
Cushman,  of  the  Boston  Society  of  Natural  History,  for  his  excellent 
drawings  of  fossils;  to  Prof.  Charles  D.  Wolcott,  Director  of  the  United 
States  Geological  Survey,  for  his  assistance  in  naming  several  of  the  Cam- 
brian fossils,  and  also  for  aid  in  the  construction  of  the  geological  map ;  and 
to  Mr.  Richard  A.  Hale  of  Lawrence,  Mr.  John  L.  Gardner,  2d,  of  Boston, 
and  others,  for  photographs  used  in  this  voltmie.  My  thanks  are  also  due 
to  Mr.  John  Robinson,  of  the  Peabody  Museum,  for  his  interest  and 
early  encouragement  of  my  work;  to  Prof.  Edward  S.  Morse,  Director 
of  the  Peabody  Museum,  for  valuable  advice  in  relation  to  the  paleon- 
tology of  the  County ;  and  to  Mr.  George  Francis  Dow,  Secretary  of  the 
Essex  Institute,  for  assistance  in  revising  my  manuscript.  Lastly,  my 
most  grateful  thanks  are  due  to  Mr.  David  Pingree,  of  Salem,  without 
whose  generous  aid  this  work  would  not  have  been  accomplished.  It  is 
also  a  pleasure  to  record  my  appreciation  of  the  spirit  of  cooperation  dis- 
played by  landowners  and  others  in  aU  parts  of  the  Cotmty,  and  my 
thanks  are  also  due  to  Mr.  Woodbury  Page  Conant,  of  Salem,  and  Mr. 
Joel  Kimball,  of  Beverly,  as  well,  who  have  accompanied  me  on  many 
long  walks  in  out-of-the-way  places  and  in  the  northern  part  of  the 
County. 


CONTENTS 


CHAPTER  I.  PAGE 

Physical  geography 21 

Watersheds 21 

Springs 22 

Drainage  and  formation  op  valley  systems 27 

River  systems 27 

Surface  features    34 

Peat  deposits 34 

Geological  distribution  of  plants 34 

CHAPTER  II. 

Coast— line  topography ,   .  45 

Rocky  headlands 45 

Smooth  or  regular  coast— lines 45 

Drowned  river  valleys  dub  to  subsidence 46 

Subsidence      51 

Sea  beaches 58 

Sand— dunes 62 

Erosion  of  the  shore  by  wave— action 68 

CHAPTER    III. 

Outcrops  of  bed— rock 76 

Stratified  rocks  of  sedimentary  origin 76 

Metamorphism 76 

Cambrian  rocks 83 

Hornblende  epidote  gneiss 90 

Ancient  rocks  of  sedimentary  origin  on  Cape  Ann      94 

Slate  or  mica— schist 97 

Sandstone 117 

Limestone 121 

CHAPTER  IV. 

The  eruptive  plutonic  rocks      125 

Quartz  augite  diorite 125 

Hornblende  diorite        129 

CHAPTER  V. 

Hornblende  granite       150 

Micrographic  granite 154 

Porphyritic  granite 166 

CHAPTER  VI. 

Muscovite  biotite  granite 168 

Paisanite 173 

7 


8  CONTENTS 

CHAPTER  VII.  PAGE 

The  syenite  rocks i77 

The  syenites  of  Salem  Neck  and  vicinity 178 

essexite 185 

Salemite      186 

Nepheline  syenite 189 

Quartz  augite  syenite  or  akbrite '.    .    .    .  190 

pulaskite 201 

Nordmarkite      201 

SoLVSBERGITB         202 

BlOTITE    TINGUAITE 205 

AeGIRINE    TINGUAITE    OR    ANALCITE    TINGUAITE 2O9 

Umptekite  gabbro 210 

Keratophyre      214 

CHAPTER  VIII. 

Igneous  volcanic  rocks 222 

CHAPTER  IX. 

The  minerals  op  Essex  County      230 

CHAPTER  X. 

The  quaternary  pleistocene  period,  glacial  ice  epoch 253 

Eskers      259 

Evidences  of  sea  beaches  at  inland  points      272 

Subglacial  drumlins 277 

Wash— plains 278 

Kames  and  ice-block  holes 283 

Post-pleistocene  sand  and  gravel 295 

Drumlins  carved  by  landslides 344 

CHAPTER  XI. 

Clays 357 

Residual  clays 357 

Upper  clays 357 

Manufactures  of  clay 358 

Glacial  marine  or  leda  clays 363 

Summary  of  subsidence  and  elevation .■    •    ■  37° 

Recession  of  the  ice-sheet 373 

CHAPTER  XII. 

Paleontology  of  the  Cambrian  rocks 380 

APPENDIX  A.     Surface  areas 393 

APPENDIX  B.     Elevations  of  drumlins 395 

APPENDIX  C.     Elevations  of  bed-rock  hills 399 

APPENDIX  D.     Lakes  and  ponds  in  the  county 400 

APPENDIX  E.     Geological  succession  of  the  rock  formations 402 

APPENDIX  F.     Chemical  analysis  of  the  rocks 404 

APPENDIX  G.     Bibliography 40S 

Map  of  Essex  County,  showing  geological  outcrop,  etc In  Pocket 


LIST    OF    ILLUSTRATIONS 


Page 

Pig.     I.     Portrait  of  the  author Frontispiece 

Fig.     2.     Merrimac  river  at  the  Lawrence  dam.     Winter  of  1897.     Photograph 

by  Richard  A.  Hale 20 

Fig.     3.     Merrimac  river  at  the  Lawrence  dam,  during  the  spring  freshet. 

Photograph  by  Richard  A.  Hale      20 

Fig.     4.     Merrimac  river  at  Mitchell's  falls,  during  low  water,  October  3,  1897. 

Photograph  by  Richard  A.  Hale      24 

Fig.     5.     Merrimac  river  at  Mitchell's  falls,  during   low  water,  1897.     Kim- 
ball's island  at  the  right.     Photograph  by  Richard  A.  Hale  ...        24 

Fig.     6.     Mouth  of  the  Spicket  river,  Lawrence.     Photograph  by  Richard  A. 

Hale 26 

Fig.     7.     Spicket  river  below  the  Globe  Mills  dam,  Lawrence.     Photograph 

by  Richard  A.  Hale 26 

Fig.     8.     Ipswich  river  at  the  Middleton  Paper  Mill  dam 30 

Fig.     9.     Ipswich  river  in  Middleton,  as  seen  from  the  bridge  on  the  Danvers 

road ^o 

Fig.   10.     Ideal  vertical-section  across  Essex  County,  showing  sections  of  the 

eruptive,  volcanic  and  sedimentary  rocks 32 

Fig.   II.     Chestnut   trees    (Castanea   Americana)    growing   upon   hornblende 

granite  soil  on  the  Burley  Farm,  Danvers 36 

Fig.   12.     Bedded  slates  and  limestones  at  East  point,  Nahant 38 

Fig.   13.     Hornblende  granite  headland  at  Eastern  point,  Gloucester.     Photo- 
graph by  Babson 38 

Fig.   14.     Gap  Head  and  Straitsmouth  island,  Rockport,  showing  an  augite 

syenite  contact  with  hornblende  granite 42 

Fig.   15.     Squam  river  from  West  Gloucester,  showing  tidal  marshes.     Photo- 
graph by  John  L.  Gardner,  2d 42 

Fig.   16.     Tidal  marsh  at  Rowley.     View  from  the  railroad  at  high  tide,  Plum 

island  in  the  distance 44 

Fig.   17.     Lagoon,  west  of  Jeffrey's  Neck,  Ipswich,  showing  tidal  marsh,  and 

drumlins  in  the  distance 44 

9 


10  LIST  OF  ILLUSTRATIONS 

Page 
Fig.   i8.     Parker  river  below  the  Byfield  Woolen  Mills,  at  low  tide 48 

Fig.  19.     Parker  river  below  the  Byfield  Woolen  Mills,  at  high  tide 48 

Fig.  20.     Saugus  river  marshes  at  high  tide,  showing  drowned  topography 

due  to  subsidence 50 

Fig.  21.  Saugus  river  marshes  at  high  tide,  from  the  Lynn  and  Boston  turn- 
pike, looking  towards  Lynn      50 

Fig.   22.     Waters  river,  Danversport,  at  low  tide,  the  Beverly  shore  in  the 

distance 54 

Fig.  23.  Crane  river,  Danversport,  at  nearly  low  tide,  showing  the  meander- 
ing of  the  stream 54 

Fig.   24.     Forest  river,  Salem,  at  low  tide.     Jeggles'  island  in  the  foreground 

and  Legg's  hill  in  the  distance 56 

Fig.  25.     Forest  river,  Salem,  above  the  dam,  at  low  tide;  from  Legg's  hill  .    .        56 

Fig.   26.     Mingo  beach,  Beverly  (1894),  showing  submerged  peat-beds,  and 

logs  and  stumps  of  forest  trees 60 

Fig.   27.     Pond  beach,  Nahant  (1894),  showing  submerged  stumps  of  white 

pine  trees 60 

Fig.  28.     Ideal  section  of  a  sea  beach,  of  which  Plum  island  beach  is  a  type  .        64 

Fig.  29.     Ideal  section  of  Ipswich  beach 64 

Fig.  30.     Off-shore   bar  at   Ipswich   beach,   showing  cuspated   foreland  and 

lagoon 66 

Fig.  31.  Ipswich  beach  from  the  top  of  Castle  hill,  showing  cuspated  fore- 
land and  off-shore  bar 66 

Fig.  32.  View  from  Gale's  point,  Manchester,  at  low  tide,  showing  the  follow- 
ing islands:  House,  Misery,  Ram,  Baker's,  Eagle,  and  Lowell  .    .        70 

Fig.  33.  Coffin's  beach,  West  Gloucester,  from  Black  Rocks  to  the  Loaf, 
showing  ripple  marks  and  cuspated  drifting  of  sand.  Ipswich 
beach  and  Plum  island  in  the  distance 70 

Fig.  34.  Coffin's  beach,  West  Gloucester,  showing  sand-dunes  of  Post- 
Pleistocene  drift-sand 72 

Fig.  35.     Post-Pleistocene  wind-blown  sand-dune  at  Castle  Neck,    Ipswich, 

showing  stratification  of  the  sand 72 

Fig.  36.     Ideal  cross-section  from  Hog  island,  Essex,  to  Ipswich  beach    ...        74 

Fig.  37.      Post-Pleistocene  wind-blown  sand  overwhelming  an  apple  orchard 

on  the  Lakeman  farm.  Castle  Neck,  Ipswich 74 

Fig.  38.     Sand-spit  oft  Castle  Neck,  Ipswich,  as  seen  from  Hog  island,  looking 

across  Castle  river  .    -. 78 

Fig.  39.     Continuation  of  the  sand-spit  off  Castle  Neck,  Ipswich,  as  seen  from 

Hog  island.     Glacial  drift  boulders  appear  in  the  foreground    .    .        78 


Fig. 

41- 

Fig. 

42. 

Fig. 

43- 

Fig. 

44. 

Fig. 

45- 

Fig. 

46. 

LIST  OF  ILLUSTRATIONS  11 

Page 
Fig.  40.      Sand-dimes  on  a  rocky  headland  near  Coffin's  beach,  West  Glouces- 
ter.    Photograph  by  John  L.  Gardner,  2d 80 

Sand-dunes  south  of  Coffin's  beach,  West  Gloucester 80 

Kame  ridge  on  south  bank  of  Castle  river,  north  of  Hog  island, 
Essex.  Ipswich  lighthouse  and  Plum  island  in  the  distance  at 
the  left      82 

Barrier  beach  between  Clifton  and  Marblehead  Neck  (July,  1895), 
showing  sea- worn  pebbles  washed  into  windrows  by  the  tides   .    .        82 

Ideal  vertical-section  across  Salem  harbor,  showing  existing  strata 
of  Cambrian  rocks 86 

Hornblende  epidote  gneiss  cut  by  a  coarse  hornblende  granite. 
Crooked  pond,  Boxford 88 

Inclusion  of  hornblende  epidote  gneiss  in  foliated  quartz  hornblende 
diorite.  A  narrow  vein  of  the  diorite  cuts  through  the  gneiss 
upon  which  the  watch  is  resting.  Southeast  of  Crooked  pond, 
Boxford 88 

Fig.  47.     Photomicrograph    of   hornblende    epidote   gneiss.     Crooked   pond, 

Boxford 92 

Fig.  48.     Cave  in  ledge  of  quartz  hornblende  diorite  east  of  Crooked  pond, 

Boxford 92 

Fig.  49.     Merrimac  river  flowing  under  the  Chain  bridge  at  Newburyport. 

Quartz  diorite  rock  on  both  sides  of  the  river 96 

Fig.  50.     Cambrian  slaty  sandstone  ledge  at  South  Lawrence,  used  (1901)  for 

road  material 96 

Photomicrograph  of  schiefierhomfels.  West  cove.  Misery  island  .    .      100 

Photomicrograph  of  quartzite  sandstone.  South  Georgetown.    ...      100 

Cambrian  limestone  and  chert.  East  point,  Nahant 104 

Cambrian  limestone  and  chert  cut  by  a  massive  basalt  dyke.  North 
of  Pulpit  rock.  East  point,  Nahant 104 

Hornblende  diorite  ledge  on  the  Pickman  estate.  South  Salem      .    .      108 

Hornblende  diorite  ledge  in  process  of  removal  by  the  Massachu- 
setts Broken  Stone  Company  (1898),  Castle  hill,  Salem 108 

Hornblende  diorite  outcrop  in  the  "Nubble  Squid,"  Groveland    .    .      112 

Split  boulder  of  hornblende  diorite  near  the  "Nubble  Squid,"  Grove- 
land  112 

Devil's  den,   Newbury,  showing  limestone   and    serpentine  in    the 

foreground 116 

Devil's  den,  Newbury,  showing  a  quartz  hornblende  diorite  forma- 
tion     116 


Fig. 

SI- 

Fig. 

52- 

Fig. 

S3- 

Fig. 

54. 

Fig. 

55- 

Fig. 

56. 

Fig. 

S7- 

Fig. 

58- 

Fig. 

S9- 

Fig. 

60. 

12  LIST  OF  ILLUSTRATIONS 

Page 
Fig.  6i.     Stickney  boulder,  Groveland.     A  hornblende   diorite  rock   resting 

upon  an  outcropping  ledge  of  hornblende  diorite 120 

Fig.  62.  Split  boulder  of  hornblende  diorite,  near  the  Stickney  boulder.  Grove- 
land  120 

Fig.  63.     Norseman's   rock,   a   quartz   hornblende    diorite   outcrop   in   West 

Newbury 124 

Fig.  64.     Cradle  rock,  Groveland,  a  glacial  perched  boulder  of  diorite,  resting 

upon  an  outcropping  ledge  of  diorite 124 

Fig.  65.  Ordway  boulder,  Byfield,  a  glacial  erratic  of  foliated  quartz  horn- 
blende diorite      128 

Fig.  66.  Haystack  boulder,  Newbury.  A  glacial  erratic  of  quartz  horn- 
blende diorite,  probably  removed  from  the  ledge  six  hvmdred  feet 
distant  at  the  north 128 

Fig.  67.  A  glacial  erratic  boulder  of  quartz  augite  diorite  located  a  short 
distance  from  the  Haystack  boulder,  Newbury.  Length,  28*  feet 
and  width,  18  feet.  Upper  surface  is  well  glaciated.  The  nearest 
outcrop  of  this  formation  in  the  line  of  glaciation  is  at  Amesbury.     132 

Fig.  68.     Foliated  granite  with  inclusions  of  quartz  diorite,  at  the  base  of 

Long  hill,  Boxford      132 

Fig.  69.  Massive  and  foliated  quartz  hornblende  diorite  outcrop  with  intru- 
sions of  coarse  vein-granite.     Lovering's  mountain,  Boxford     .    .      136 

Fig.   70.     Hornblende  diorite  at  Ledge  Hill  park,  Salem,  showing  glaciated 

surface 136 

Fig.   71.     Photomicrograph  of  white  limestone,   showing  serpentine  pseudo- 

morphs.     Devil's  den,  Newbury 140 

Fig.   72.     Photomicrograph  of  a  biotite  concretion  in  mica  hornblende  diorite 

at  Middleton 140 

Fig.  73.  Legg's  hill,  Salem,  a  diorite  ledge  with  summit  glaciated  and  stripped 
of  debris.  Kame  topography  and  washed  gravels  shown  in  the 
foreground i44 

Fig.   74.     Quartz  hornblende  diorite  outcrop  at  Clifton,  showing  broken  and 

bizarre  form  of  headland 144 

Fig.   75.     Hornblende  granite  quarry  at  Rockport,  showing  jointing  of  the 

formation 148 

Fig.  76.  Hornblende  granite  quarry  at  Lanesville,  Gloucester,  showing  grad- 
ual increase  in  thickness  of  the  joint  planes 148 

Fig.   77.     Raccoon  rocks,   Manchester,   an  outcropping  ridge   of  hornblende 

granite 152 

Fig.   78.     Hornblende  granite  outcrop  in  the  Raccoon  rocks,  Manchester    .    .      152 


Fig. 

80. 

Fig. 

81. 

Fig. 

82. 

Fig. 

83- 

Fig. 

84. 

Fig. 

85- 

Fig. 

86. 

Fig. 

87. 

Fig. 

88. 

Fig. 

8q. 

LIST  OF  ILLUSTRATIONS  13 

Page 
Fig.   79.     Hornblende  granite  outcrops,  between  which  a  basic  dike  rock  has 
been   removed   by   disintegration.     South   from   Coffin's   beach, 
West  Gloucester 156 

Hornblende  granite  boulder  at  Essex,  32  feet  high,  35  feet  wide,  40 
feet  long;  estimated  weight,  3,763  tons 156 

Photomicrograph  of  actinolite  in  a  mass  of  Fayalite,  Rockport  .     .      160 

Photomicrograph  of  biotite  olivin  peridotite,  Skug  river,  Andover   .      160 

Muscovite  biotite  granite,  foliated,  Jones  quarry.  South  Lawrence   .      164 

Aplitic  granite  dike  cutting  quartz  hornblende  diorite,  at  Clifton, 

Marblehead 164 

Granitic  white  gneiss  arkose,  Jones  quarry,  West  Andover    ....      170 

Granitic  white  gneiss,  with  much  muscovite,  Jones  quarry.  South 

Lawrence      170 

Quartz  augite  syenite,  Poorhouse  hill,  Beverly 176 

Augite  syenite,  Dudley  L.  Pickman  estate,  Beverly  Cove 176 

Brecciated  hornblende  diorite  cut  by  veins  of  pulaskite  syenite,  near 
Beverly  bridge,  Salem 180 

Fig.  90.     Hornblende  diorite  cut  by  veins  of  pulaskite  syenite  and  diabase, 

near  Beverly  bridge,  Salem 180 

Fig.  91.     Salemite,  on  the  south  side  of  Fort  avenue,  Salem  Neck 184 

Fig.  92.     Essexite,  cut  by  veins  of  pulaskite  syenite  and  camptonite,  north 

side  of  Fort  avenue,  Salem  Neck 184 

Fig.  93.     Photomicrograph  of  Essexite  from  Salem  Neck 188 

Fig.  94.     Photomicrograph  of  Salemite  from  Salem  Neck 188 

Fig.  95.     Biotite  tinguaite  dike  in  augite  syenite  ledge,  Manchester 192 

Fig.  96.  Nepheline  syenite  with  veins  of  pulaskite  and  hornblende  gabbro 
and  also  showing  erosion  of  boulders  in  situ.  Cat  cove,  Salem 
Neck 192 

Fig.  97.     Photomicrograph  of  augite  syenite,  or  akerite.  South  Salem  ....      196 

Fig.  98.  Photomicrograph  of  microcline  in  augite  syenite  from  Briscoe  hill, 
Beverly,  showing  albite  intergrowths  across  the  twinned  micro- 
cline   196 

Fig.  99.     Pulaskite  syenite  formed  into  boulders  in  situ  by  disintegration  and 

erosion,  Salem  Neck 200 

Fig.  100.   Pulaskite     syenite     veins    cutting    decayed    hornblende    gabbro, 

Salem  Neck 200 

Fig.  ioi.   Nordmarkite  ledge  broken  down  by  action  of  frost.  West  Glouces- 
ter     204 


14  LIST    OF    ILLUSTRATIONS 

Page 
Fig.   1 02.     Quarry  opened  in  a  ledge  of  nordmarkite,  showing  irregular  jointing 

of  the  rock,  West  Gloucester      204 

Fig.   103.     Photomicrograph  of  nordmarkite,  Gloucester      208 

Fig.   104.     Photomicrograph  of  aegirine  tinguaite  from  Pickard's  point,  Man- 
chester     208 

Fig.  105.  Photomicrograph  of  aegirine  syenite  from  Gale's  point,  Manchester, 
showing  the  aegirine  crystals  arranged  in  a  plane  with  ortho- 

clase 2^2 

Fig.   106.     Photomicrograph  of  aegirine  syenite  from  Gale's  point,  Manchester     212 

Fig.   107.     Salemite  outcrop  (in  the  foreground)  and  ledge  of  umptekite  gab- 

bro  (beyond  the  road),  Salem  Neck       216 

Fig.   108.     Umptekite  gabbro  cut  by  veins  of  pulaskite  syenite,  Salem  Neck    .      216 

Fig.   109.     Photomicrograph   of   hornblende   umptekite   gabbro   from   Salem 

Neck 22° 

Fig.   1 10.     Photomicrograph  of  umptekite  gabbro  from  eastern  side  of  Misery 

island 220 

Fig.   III.     Keratophyre  from  the  harbor  side  of  Marblehead  Neck.     Anor- 

thoclase  crystals  appear  as  white  spots 224 

Fig.   112.     Foliated   aporhyolite,  from  a  bare    ledge    off   Marblehead    Neck 

showing  weathered  surface 224 

Fig.   113.     Photomicrograph  of  an  anorthoclase  crystal  in  keratophyre  from 

Marblehead  Neck      228 

Fig.   114.     Photomicrograph  of  an  anorthoclase  crystal  in  keratophyre  from 

Marblehead  Neck      228 

Fig.   115.     Castle  hill,  Saugus,  a  massive  outcrop  of  aporhyolite,  an  ancient 

volcanic  rock 232 

Fig.   116.     Castle  hill,  Saugus 232 

Fig.   117.     Photomicrograph  of  liparite,  a  quartz  porphyry  aporhyolite  with 

spherulites 236 

Fig.  118.  Aporhyolite  outcrop  on  the  harbor  side  of  Marblehead  Neck,  show- 
ing the  flow  of  the  lava 236 

Fig.   119.     Aporhyolite,   showing  weathered  surface.  High  rock,  Marblehead 

Neck 240 

Fig.  120.     Banded  aporhyolite,  showing  the  flow  of  the  magma  previous  to 

its  consolidation,  Bowden's  point,  Marblehead  Neck 240 

PiG.   121.     Aporhyolite  concretion,  Marblehead  Neck 244 

Fig.   122.     Aporhyolite  conglomerate.  South  Gooseberry  island,  Salem  harbor     244 

Fig.   123.     The   minerals    of    Essex  County,    as  exhibited    at    the    Peabody 

Museum,  Salem 248 


LIST   OF  ILLUSTRATIONS  15 

Page 
Fig.  124.  View  in  Topsfield  looking  across  the  geographical  center  of  Essex 
County  showing  the  even  sky-line  and  roiinded  outlines  of  the 
surface.  The  Ipswich  river  is  seen  in  the  center  of  the  picture 
and  the  drumlins,  Hunslow  hill  and  Prospect  hill  are  outlined 
against  the  sky 252 

Fig.   125.     Quarry  of  the  Rockport  Granite  Company  at  Rockport,  showing 

the  general  structvu^e  of  the  hornblende  granite  rock 256 

Fig.  126.     Glaciated  stones  found  in  boulder-till  at  North  Andover     ....      256 

Fig.  127.     Glaciated  diabase  dike  rock  near  Flying  point,  Marblehead  Neck   .     258 

Fig.  128.  Remarkable  glacial  groove,  30  feet  long,  3  feet  wide  and  sJ  inches 
deep,  on  the  surface  of  a  hornblende  diorite  ledge  in  Ledge  Hill 
park,  Salem 258 

Fig.  129.     "  Sheep  backs "  or  roc/ies  woMtowwm,  at  South  Georgetown.    Small 

elevations  of  bed-rock  covered  by  drift  gravels      262 

Fig.   130.     "Sugar-loaf"  hill  or  roche  moutonnSe  at  Tops&eid.     Arkose  granite 

conglomerate  covered  by  a  thin  coating  of  glacial  drift     ....      262 

Fig.  131.     Ideal  section  of  an  ice-block  hole 264 

Fig.  132.     Ideal  section  of  an  alluvial  plain  bordering  the  front  of  a  glacier   .      264 

Fig.   133.     The  long  esker  near  Dodge  street.  North  Beverly 268 

Fig.   134.     The  long  esker  near  Dodge  street,  North  Beverly.     View  looking 

northwesterly  across  Dodge  street 268 

Fig.   135.     Serpentine  esker  at  Willowdale  in  Hamilton 270 

Fig.  136.  Bishop's  swamp,  Danvers,  an  ice-block  hole.  View  from  the  base 
of  Nichols'  hill,  showing  the  gravels  deposited  from  the  surface  of 
glacial  ice 270 

Fig.  137.     Serpentine  esker  on  the  Gwinn  farm  near  Willowdale  in  Hamilton     274 

Fig.  138.     Serpentine  esker  at  Willowdale  in  Hamilton,  illustrating  reticulated 

kames,  and  knob  and  basin  topography 274 

Fig.   139.     Norwood's  pond.  North  Beverly,  having  esker  terraces  on  both  sides. 

View  from  the  main  terrace 276 

Fig.  140.  Double-terrace  esker  on  the  north  side  of  Longham  brook,  Wen- 
ham,  showing  a  kettle  hole 276 

Fig.   141.     Kames  and  kettle  holes  near  Forest  river,  Salem 280 

Fig.  142.     Steep-sided  esker  west  of  Norwood's  pond.  North  Beverly  ....      280 

Fig.  143.     Knob  and  basin  topography,  showing  kettle  holes  southwest  of  the 

"dungeons"  in  Marblehead 282 

Fig.  144.     Glacial  till  and  gravel  cone  on  the  south  side  of  Forest  river,  Salem     282 
Fig.   145.     Hog  island,  Essex,  at  low  tide,  a  typical  drumlin  showing  ado- 
lescent grass-grown  scarps  caused  by  landslides 286 


16 

Fig. 

146. 

Fig. 

147- 

Fig. 

148. 

Fig. 

149. 

Fig. 

ISO- 

Fig. 

151- 

Fig. 

152- 

Fig. 

153- 

Fig. 

IS4- 

Fig. 

iSS- 

Fig. 

156. 

Fig. 

157- 

Fig.  158. 

Fig.  159. 
Fig.  160. 

Fig.  161. 

Fig.  162. 
Fig.  163. 

Fig.  164. 
Fig.  165. 

Fig.  166. 

Fig.  167. 


LIST    OF    ILLUSTRATIONS 

Page 

Mussey  hill,  Rowley,  as  seen  from  the  rolling  sand-plain  towards 
the  southwest 286 

Old  Town  hill,  Newbury.  View  from  the  southwest  across  the 
tidal  marsh 288 

Eagle  hill,  Ipswich,  a  small  drumlin,  with  base  cut  by  wave  action     288 

Hog  island,  Essex,  at  high  tide,  the  rocks  in  the  foreground  are  the 
remnants  of  a  stone  wall  on  either  side  of  a  road  which  has  been 
submerged  because  of  subsidence 292 

Great  hill,  Haverhill,  as  seen  from  Whittier's  hill 292 

Drumlins  on  Jeffrey's  Neck,  Ipswich,  as  seen  from  Eagle  hill  ...  294 

Turkey  hill,  a  drumlin  at  East  Haverhill 294 

Whittier's  hill,  a  drumlin  at  Haverhill 298 

Ice-berg  or  kettle  hole,  in  the  "dungeons,"  Marblehead 298 

Ice-berg  holes  in  kame  gravels  near  Legg's  hill,  South  Salem. 
Legg's  hill,  a  wave-swept  outcrop  of  hornblende  diorite,  may  be 
seen  in  the  distance      300 

Ice-berg  hole  in  over-wash  gravels,  also  showing  a  short  kame 
within  the  hole.     The  "dungeons,"  Marblehead 300 

Over-wash  gravels,  ice-berg  holes,  and  short  reticulated  kames. 
Winter  scene  at  the  "dungeons,  "  Marblehead.  Legg's  hill  at  the 
left      304 

Winter  scene  at  the  "dungeons,"  Marblehead.  Legg's  hill  at  the 
right 304 

Legg's  Hill  pond,  Salem.     An  ice-block  hole  nearly  filled  by  peat      306 

Crooked  pond,  Boxford.  An  ice-block  hole  which  has  become  a 
nearly  filled  pond 306 

Ice-berg  hole  in  an  out-wash  sand-plain,  east  of  Wenham  swamp. 
Arbor  street,  Wenham 310 

Ice-berg  hole  on  the  east  side  of  Arbor  street,  Wenham 310 

Kame  terrace,  marking  an  ice  contact  on  the  southeastern  shore 
of  Leach's  swamp,  an  ice-block  hole.  West  Wenham 312 

Another  view  of  the  above      312 

Wenham  lake.  The  tree-covered  point  at  the  left  •  is  a  gravel 
terrace  marking  an  ice  contact 316 

Drainage  crease  above  a  landslide  on  the  southwestern  side  of 
Hog  island,  Essex 3^6 

Inland  sand-dunes  at  East  Georgetown  near  the  Byfield  meeting- 
house        31S 


LIST  OF  ILLUSTRATIONS  17 

Page 
Fig.   i68.     Another  view  of  the  above 318 

Fig.   169.     Cross-section  of  a  terrace  at  High  street,  Newburyport 322 

Fig.   170.     Glacial  groove  in  a  quartz  diorite  ledge  on  the  east  side  of  Green 

street,  Newbury 322 

Fig.   171.     Merrimac  river.     The  bend  below  Mitchell's  falls,  showing  deposits 

of  river  silts.     Kame  gravels  in  the  foreground 324 

Fig.  172.  Enclosed  block  of  ferruginous  gravel  probably  deposited  in  a  mass 
during  late  glacial  times.  Sand-plain  east  of  railroad  station, 
Hampton,  N.  H 324 

Fig.   173.     Merrimac  river  at  Mitchell's  falls.     Lone  Tree   hill,  Methuen,  in 

distance 326 

Fig.   174.     Ship  rock,  Peabody.     An  erratic  boulder  of  hornblende  granite      .      326 

Fig.   175.     Hornblende   granite    boulder  perched   upon    boulders   eroded   in 

situ,  Peabody.     Photograph  by  Richards  B.  Mackintosh      .    .    .      330 

Fig.  176.  Hornblende  granite  boulders  eroded  in  situ,  Peabody.  Photo- 
graph by  Richards  B.  Mackintosh 330 

Fig.   177.     Hornblende  granite  ledge  at  Peabody,  showing  horizontal  jointing. 

Photograph  by  Richards  B.  Mackintosh 332 

Fig.   178.     Syenite  ledge  stripped  of  debris  and  rounded  by  the  action  of 

glacial  ice.  East  Gloucester.     Photograph  by  John  L.  Gardner,  2d     332 

Fig.   179.     Niles'  pond,  Eastern  point,  Gloucester 334 

Fig.   180.     Hard-packed   bouldery  gravel  covered  by  a  moraine  of   boulders, 

Gloucester 334 

Fig.  181.  Moraines  of  boulders  at  Rockport,  northeast  of  Dogtown  common, 
showing  a  halting  place  of  the  glacial  ice  during  its  retreat  from 
the  region 338 

Glacial  erratic  boulders  at  Dogtown  common,  Gloucester     ....      338 

Moraines  of  boulders,  east  of  Beach  Grove  cemetery,  Rockport  .    .      340 

Another  view  of  the  above      340 

Wolf  hill,  Gloucester.     Perched  glacial  boulders  ^ipon  its  summit. 
Photograph  by  John  L.  Gardner,  2d 342 

Fig.  186.  Drainage  crease  at  Manchester,  the  outlet  from  a  large  valley  at 
the  west  which  was  filled  with  glacial  ice.  Photograph  by 
W.  T.  Clark 342 

Fig.  187.  Cape  pond,  Rockport 346 

Fig.  188.  Incipient  landslide  on  Brake  hill.  West  Newbury 346 

Fig.  189.  Mature  landslide  on  Long  hill,  West  Newbury 348 

Fig.  190.  Another  view  of  the  above      348 


Fig. 

182, 

Fig. 

183. 

Fig. 

184. 

Fig. 

18s. 

18  LIST   OF   ILLUSTRATIONS 

Page 
Fig.  191.     Adolescent    landslide,  Hog  island,  Essex.      The  slide  has  formed 
a  bench  near  the  fifty-foot  contotir  line  from  which  spring-water 
continually  flows  down  the  hill 350 

Fig.  192.  North  ridge,  Jeffrey's  Neck,  Ipswich,  as  seen  from  Eagle  island, 
showing  live  landslides  around  the  base  of  the  ridge  and  above 
a  grass-grown  bench  of  an  earlier  slide 350 

Fig.   193.     Plan  of  the  valley  of  Porter's  river,  East  Danvers 354 

Fig.  194.  Clay -beds  covered  by  a  thin  coating  of  river  silts  and  sand.  West 
side  of  the  Merrimac  river  near  Mitchell's  falls,  Haverhill. 
Photograph  by  Richard  A.  Hale 356 

Fig.   195.     Danversport,   showing    the    area    covered  by  brick-clays.     Folly 

hill  in  the  distance 356 

Fig.   196.     Leda-clay   at  the   bottom   of  the  Edward  Carr   clay-pit,    Liberty 

street,  Danversport 360 

Fig.  197.  Peabody  Pottery  Company's  clay-pit  near  Purchase  street,  Dan- 
vers       360 

Fig.   198.     Cross-section  of  the  valley  of  Crane  river,  Danvers 362 

Fig.   199.     Cross-section  of  the  clay-pit  of  the  Peabody  Pottery  Company, 

near  Purchase  street,  Danvers 362 

Fig.  200.     Cross-section  of  the  valley  of  Porter's  river,  Danvers 366 

Fig.  201.     Cross-section  of  the  clay-pit  of  the  Edward  Carr,  Liberty  street, 

Danvers      366 

Fig.   202.     Fossil  starfish,  Astericanthian  Linckii,  Miiller,  found  in  the  Richard 

Graham  clay-pit,  Lynn 369 

Fig.  203.     Longham  basin,  North  Beverly,  showing  escarpment  at  the  right 

and  in  the  background 373 

Fig.  204.     Gravel-pit  at  Legg's  hill,  Salem,  showing  kame  gravels 373 

Fig.  205.     Portlandia   Arctica,  Gray.     From   the  Peabody  Pottery  clay-pit. 

Purchase  street,  Danvers 376 

Pig.  206.  Glacial  marine  fossils  found  in  leda-clay  in  the  Edward  Carr  clay- 
pit.  Liberty  street,  Danvers 378 

Fig.  207.     Glacial  marine  fossils  found  in  leda-clay  at  Danvers 382 

Fig.   208.     Cambrian  fossils  from  Nahant  and  Jeffrey's  ledge 386 

Pig.  209.     Cambrian  fossils  from  Topsfield  and  Nahant 390 


m^ 


^m:^ 


Fig,    2.  —  WIERRIWIAC    RIVER    AT    THE    LAWRENCE    DAM, 
Winter  of    I  897. 


Fig.   3.  — MERRIMAC    RIVER    AT   THE    LAWRENCE    DAM. 
During  a  spring  freshet. 


THE    PHYSICAL    GEOGRAPHY,  MINERALOGY,  AND 

PALEONTOLOGY    OF   ESSEX    COUNTY, 

MASSACHUSETTS 


CHAPTER   I 

PHYSICAL   GEOGRAPHY 

Essex  County,  Massachusetts,  is  situated  between  latitude  42°  53'  10.49" 
north,  and  42°  25'  09.20"  south;  and  between  longitude  70°  34'  46.28" 
east,  and  71°  i5'is.33"  west.  The  County  contains  355,840  acres,  of  which 
21,789  acres  are  tidal  marsh  covered  by  sea-water  at  high  tide;  18,000 
acres  are  covered  by  sea-water  in  the  form  of  bays,  harbors,  and  drowned 
river  valleys;  and  16,500  acres  are  covered  with  fresh-water  ponds,  lakes, 
rivers,  and  swamps;  leaving  299,551  acres  occupied  by  city  and  village 
sites,  woodlands  and  tillage  lands.'  The  number  of  acres  within  the 
territorial  limits  of  each  town  and  city  is  inserted  as  Appendix  A. 

Watersheds.  —  The  principle  watersheds  in  the  County  are  in  the 
valleys  occupied  by  extended  streams:  the  Saugus  river  at  the  south, 
the  Ipswich  and  Parker  rivers  flowing  across  the  central  part  of  the  area, 
the  Merrimac  river  in  the  northern  part  of  the  County,  and  a  number  of 
small  tributaries  which  empty  into  the  extended  streams,  together  with  a 
few  small  streams  rising  near  the  coast-line  and  emptying  into  the  sea. 
Examples  of  the  latter  are:  Mill  brook,  which  rises  in  a  swamp  one  mile 
north  of  Pride's  Crossing  and  empties  into  the  sea  between  Beverly  Farms 
and  West  Manchester;  Beaver  Dam  and  Saw  Mill  brooks  in  Manchester; 
and  Frost-fish  brook,  Danvers,  which  empties  into  Porter's  river,  a  drowned 
river  valley  or  tidal  stream  flowing  in  and  out  through  Beverly  harbor. 

Several  interesting  divides  in  these  streams  show  almost  exactly  the 
height  of  land,  which  is  remarkable  as  the  water  fall  is  very  slight.  The 
valleys  are  nearly  level  and  the  streams  flow  sluggishly  except  in  times  of 
flood.     One  of  these  divides  occurs  in  a  meadow  in  Danvers,  in  the  valley 

'  In  1905,  there  were  seven  cities  and  twenty-eight  towns  in  the  County. 
21 


22  WATERSHEDS   AND    SPRINGS 

between  Goodale's  and  Fair  Maid  hills.  During  the  winter  the  ice  forming 
over  the  surface  becomes  frozen  into  a  mound.  A  small  brook  which 
makes  its  way  from  this  mound  flows  to  the  eastward  and  supplies  the 
head-waters  of  Crane's  river  which  flows  to  tide-water  at  Danversport. 
Another  brook  which  rises  from  this  ice  moiuid,  flows  westerly  and  joins 
Boundary  brook  between  Danvers  and  Peabody  and  empties  into  the 
Ipswich  river  in  Danvers.  Another  similar  divide  occurs  in  Topsfield, 
south  of  the  Ipswich  river,  near  a  contact  of  the  hornblende  granite  with 
the  diorite  and  the  Cambrian  limestones.  In  a  small  meadow  south  of 
Pingree's  hill,  a  brook  rising  from  a  spring  flows  westerly  under  HiU 
street  and  Rowley  Bridge  street  and  empties  into  the  Ipswich  river.  An- 
other brook  starting  from  the  same  meadow  flows  easterly  under  the  Boston 
and  Newburyport  turnpike,  thence  across  the  northern  part  of  Danvers 
to  Wenham  swamp,  and  then  into  the  Ipswich  river.  Similar  divides  in 
the  watershed  may  be  found  in  several  towns  in  the  County. 

Springs.  —  All  the  streams  in  the  County  flow  from  springs,  often 
called  boiling  springs  because  the  water  bubbles  up  with  considerable 
force  through  the  sand  or  gravel  in  the  bottom  of  the  spring.  Great 
spring,  in  Blind  Hole  swamp,  Danvers,  rises  through  eight  feet  of  peat, 
sometimes  bringing  to  the  surface  pebbles  an  inch  in  diameter.  The 
water  in  these  springs  is  always  soft,  and  percolates  through  sand  and 
gravel  soils  from  a  bed-rock  of  either  granite,  diorite,  granitic  gneiss  or 
metamorphosed  slate.  There  are  two  or  more  chalybeate  springs  in  the 
County,  one  of  which  is  at  Montserrat,  Beverly,  and  another  at  the  Mineral 
Paint  mine  in  Georgetown.  The  water  comes  to  the  surface  through 
syenite  and  slate  rocks  containing  masses  of  iron  pyrites,  lime,  soda, 
feldspar,  and  calcite.  These  minerals  when  dissolved  furnish  the  sihca, 
carbonate  of  lime,  soda,  sulphur,  and  iron  which  appear  upon  analysis. 
At  Ballardvale,  in  Andover,  is  the  well-known  Ballardvale  Lithia  spring. 
The  bed-rock  of  the  region  is  a  coarse  granitic  white  gneiss  containing  an 
abundance  of  crystals  of  white  lithia  mica,  which  are  dissolved  by  the 
carbonic  acid  in  rain-water  and  little  by  little  impregnate  the  spring- 
water. 

The  spring-waters  in  the  County  are  always  good  and  wholesome, 
containing  only  about  one  part  of  dissolved  mineral  substance  in  every 
10,000  parts  of  the  water.  In  1903,  there  were  seventeen  springs  from 
which  mineral  waters  were  sold  for  table  use,  and  numerous  springs  from 
which  waters  were  bottled  for  domestic  purposes. 

These  springs  and  streams  played  a  very  important  role  in  the  settle- 


Fig.   4.— MERRIMAC    RIVER    AT    MITCHELL'S    FALLS. 
During  low  water,    Oct.   3,    1897. 


Fig.    5.   -MERRIMAC    RIVER    AT    MITCHELL'S    FALLS    DURING    LOW    Vi/ATER,     1897. 
Kimball's  island  at  the  right. 


'i 

^L'  >(£ 

L^ 

1 

1 

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HH^BH^H^^W  f  '^S^^^fl 

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Fig.   6.-  MOUTH    OF    THE    SPICKET    RIVER,    LAWRENCE 


Fig.   7.  — SPICKET    RIVER    BELOVi'    THE    GLOBE    MILLS    DAM,    LAV^RENCE. 


RIVER    SYSTEMS  27 

ment  of  the  County,  for  the  early  settler  always  chose  a  site  for  his  house 
near  a  spring.  As  a  town  was  formed,  the  burial-ground,  the  meeting- 
house, the  school-house,  and  the  townhouse  were  usually  built  upon  a  sandy 
waste  or  a  sand-plain  where  the  soil  was  poor  and  unfit  for  cultivation  and 
in  time  such  locations  became  proverbial.  Later,  with  the  introduction  of 
aqueduct  water,  these  sand-plains  became  the  sites  of  villages  surrounding 
the  public  buildings. 

Drainage  and  Formation  of  Valley  Systems.  —  In  the  Cambrian,  Pre- 
Cambrian  and  Archean  periods,  the  longer  axes  of  all  of  the  crystalline 
rocks  were  formed  approximately  in  the  line  of  strike  of  the  Archean 
gneissic  and  the  Cambrian  sedimentary  rocks.  This  trend  is  northeast 
to  north,  and  southwest,  and  the  principal  streams  and  their  valleys 
accordingly  follow  this  general  course.  The  younger  or  consequent  stream 
valleys  are  those  which  cut  across  the  strike  of  these  gneisses  and  sedi- 
mentary rocks. 

River  Systems.  —  The  principal  river  systems  in  the  County,  with 
valleys  of  the  extended  type,  are  as  follows : 

First :  the  Merrimac,  an  extended  stream  which  takes  its  course  across 
West  Andover  to  Lawrence,  Bradford  and  Haverhill.  (See  Figs.  2,  3,  4,  5.) 
From  thence  in  its  flow  to  tide-water  it  very  nearly  follows  a  northeasterly 
course,  being  deflected  occasionally  by  hard  dike  rocks  which  cut  across 
the  stratified  beds.  At  Amesbury,  the  Powow  river,  a  consequent  stream, 
empties  into  the  Merrimac  at  Salisbury  Point.  The  Merrimac  is  here 
forced  to  cut  its  channel  southeasterly  to  avoid  a  massive  outcrop  of 
porphyritic  granite,  while  along  its  southern  bank  there  is  a  line  of  con- 
tact of  the  Cambrian  sediments  and  the  quartz  augite  diorite  rocks  ex- 
tending to  the  mouth  of  the  river. 

Second;  the  Shawsheen  river,  a  consequent  stream  of  somewhat  ex- 
tended type,  which  flows  its  entire  course,  a  distance  of  twenty-five  miles, 
northeasterly  from  the  town  of  Lincoln,  in  Middlesex  County,  to  South 
Lawrence,  where  it  empties  into  the  Merrimac. 

Third:  the  Spicket  river,  also  a  consequent  stream,  which  is  the  outlet 
of  Youth's  pond  and  Mystic  pond  in  Methuen.  (See  Figs.  6,  7.)  It  flows 
northeasterly  across  the  northern  part  of  Methuen,  then  south-southeast- 
erly to  Mystic  pond,  and  then  meanders  in  a  southeasterly  course  across 
the  southern  part  of  Methuen  to  the  city  of  Lawrence,  there  flowing  along 
the  strike  of  the  metamorphosed  slate  beds  to  the  Merrimac  river. 

Fourth:  the  Ipswich  river,  which  is  of  the  extended  type  and  rises  in 
the  meadows  of  Wilmington  and  Burlington,  winds  its  course  in  a  north- 


28  RIVER    SYSTEMS 

easterly  direction  through  meadows  in  the  line  of  strike  of  the  Cambrian 
limestone  slates  and  conglomerates  in  the  town  of  Reading  and  then 
through  Middleton  and  Topsfield  to  tide-water  at  Ipswich.     (See  Figs.  8,  9.) 

The  Parker  river  is  also  of  the  extended  type.  It  is  the  outlet  of 
Chadwick's  pond  in  West  Boxford  and  flows  southerly  and  then  north- 
easterly through  Georgetown,  West  Newbury,  and  Newbury,  at  last  empty- 
ing into  Plum  Island  river. 

Essex  river,  the  outlet  of  the  Chebacco  lakes,  is  an  extended  stream 
that  rises  in  East  Wenham  and  flows  toward  the  northeast,  draining  the 
whole  region  of  East  Hamilton,  Manchester,  and  Essex.  On  this  stream 
there  is  a  twenty-foot  fall  known  as  Essex  Falls,  where  there  is  a  sawmill. 

Other  consequent  streams  are : 

Miles  river,  the  outlet  of  Wenham  lake,  and  Pleasant  pond  brook,  the 
outlet  of  Pleasant  pond.  Both  flow  north  and  northeast  and  empty  into 
the  Ipswich  river  at  Hamilton  and  Ipswich.  Black  brook,  the  outlet 
from  Cutler's  pond,  flows  northerly,  and  after  many  meanderings  also 
empties  into  the  Ipswich  river  at  Hamilton. 

Nichols'  brook,  in  Danvers,  drains  Bishop's  and  Peters'  meadows  and 
flows  northeasterly  through  Middleton  to  Topsfield  where  it  empties  into 
the  Ipswich  river. 

Beaver  brook,  in  West  Newbury,  flows  southerly  and  southeasterly 
across  the  town,  east  of  Crane  Neck  hill,  and  empties  into  the  Parker  river. 

Mill  creek,  the  dividing  line  between  Rowley  and  Newbury,  at  the 
beginning  of  its  flow  is  known  as  the  Great  Swamp  brook,  but  at  South 
Georgetown  it  is  called  Mill  river.  Its  course  is  southeasterly  for  the  first 
mile  and  then  northeasterly  for  a  distance  of  eight  miles  to  Dummer's 
mill.  With  several  wide  detours  it  then  flows  northeasterly  and  empties 
into  the  Parker  river. 

Bull  brook,  rises  from  a  series  of  springs  in  Pine  swamp,  Ipswich,  and 
flows  northeasterly  through  the  town  of  Rowley  into  Rowley  river. 

Boston  brook,  rises  in  Andover  and  flows  three  miles  in  a  southeasterly 
direction,  then  turns  toward  the  north  for  a  mile,  and  then  to  the  south- 
east, flowing  four  miles  in  this  course  with  several  wide  meanders,  to 
Middleton  where  it  empties  into  the  Ipswich  river. 

Mosquito  brook  also  starts  from  a  spring  in  Andover  on  the  westerly 
side  of  Woodchuck  hill,  and  after  flowing  about  five  miles  in  a  northeasterly 
course  empties  into  Fish  brook,  which  flows  through  Boxford  toward  the 
southeast  in  a  winding  course  and  empties  into  the  Ipswich  river  at  Tops- 
field. 


Fig.   8.  —IPSWICH    RIVER    AT   THE    MIDDLETON    PAPER    MILL    DAM. 


p,g.    9— IPSWICH    RIVER    IN    MIDDLETON. 
As  seen  from   the   bridge  on  the   Danvers  road. 


Q. 

D 


RIVER    SYSTEMS  33 

Hewlett's  brook  and  Mile  brook  flow  from  springs  in  Boxford  and 
follow  a  southeasterly  course  into  Topsfield  where  they  empty  into  the 
Ipswich  river. 

The  stream  which  forms  the  outlet  for  Cape  pond,  at  Rockport,  flows 
southwesterly  across  Gloucester  and  empties  into  Mill  river  at  Willowdale 
in  Gloucester.  Another  brook  which  rises  in  a  swamp  at  Rockport  near 
the  Boston  and  Maine  Railroad  station,  flows  northeasterly  through  the 
village  of  Rockport  where,  south  of  King  street,  it  forms  a  pond  on  which 
ice  is  cut  for  domestic  purposes.  This  brook  empties  into  the  sea  at 
Sandy  Bay,  there  showing  that  the  tilt  of  the  granite  anticline,  on  the 
extreme  point  of  Cape  Ann,  is  toward  the  northeast. 

All  of  these  consequent  streams  are  of  sluggish  flow  with  very  slight 
fall  and  meander  through  swamps,  meadows,  and  old  ponds  in  wide  valleys 
and  sand-plains. 

South  of  Essex  County,  in  Middlesex  County,  the  Concord  and  Sud- 
bury rivers  flow  north  to  northeast  and  empty  into  the  Merrimac  river  at 
Lowell,  also  demonstrating  that  the  slope  or  tilting  of  the  land  surface 
of  Essex  County  and  the  northern  part  of  Middlesex  County  is  toward  the 
north  and  northeast.  This  is  in  an  opposite  direction  from  the  supposed 
slope  of  the  land  south  of  Cape  Cod  and  also  in  the  Connecticut  river 
valley.  The  northeasterly  to  southwesterly  valleys  of  the  Concord, 
Shawsheen,  Ipswich,  and  Merrimac  river  systems  signify  that  they  flow 
in  a  series  of  broadly  sweeping  synclinal  folds  of  the  old  Archean  gneissic 
rocks  and  Cambrian  sediments.  Measurements  across  the  upturned  edges 
of  the  Cambrian  rocks  found  in  Essex  County  prove  that  they  were  over 
10,000  feet  thick,  and  if  reconstructed  would  form  mountains  fully  two 
miles  in  height  over  our  granite  syenite  and  other  igneous  rocks.  (See 
Fig.  10.)  To  quote  from  Professor  Van  Hise,  in  his  "Principles  of  North 
American  Pre-Cambrian  Geology"  :  ^  "It  has  been  shown  that  at  a  depth  of 
30,000  feet,  more  or  less,  even  the  strongest  rocks  must  find  relief  from 
stress  by  flow,  and  hence  below  that  depth  there  must  be  a  zone,  which, 
as  respects  its  manner  of  deformation,  may  be  called  a  zone  of  flow."  If 
this  statement  of  Professor  Van  Hise  is  correct,  very  probably  this  depth 
to  the  zone  of  flow  may  have  been  under  our  Cambrian  rocks  which  are 
now  near  the  present  surface.  Should  this  be  the  case,  the  flow  and 
crumpling  of  the  granite  gneiss  and  foliated  quartz  diorites,  which  is  to 
be  seen  in  the  central  part  of  the  County,  may  have  been  formed  in  this 
zone  of  flow  beneath  the  Archean  and  Cambrian  sediments,  which  were 
'  i6th  Annual  Report  of  the  United  States  Geological  Survey,  Pt.  I,  pp.  594-598. 


34  SURFACE    FEATURES 

base-levelled  or  cut  down  to  the  level  of  the  sea  long  before  the  Tertiary- 
uplift  which  ushered  in  the  Quaternary  or  Pleistocene  period. 

Surface  Features.  —  Essex  County,  and  indeed  the  whole  of  eastern 
Massachusetts,  has  an  uneven  surface  with  numerous  outcropping  ledges 
of  bed-rock  which  are  either  base-levelled  or  have  an  elevation  varying 
from  fifty  to  one  hundred  feet  above  mean  sea-level.  The  summits  of 
these  elevations  are  bare  or  have  but  a  slight  covering  of  soil.  There  are 
a  few  higher  elevations  of  bed-rock  rising  to  about  two  hundred  feet  in 
height  and  known  as  "  Monadnocks."  Such  isolated  peaks  are  remnants 
of  the  hard  rocks  of  an  ancient  Peneplain,  which  have  withstood  the  erosive 
forces  which  have  cut  down  and  produced  the  valleys  between  them. 

The  Cambrian  rocks  are  in  part  base-levelled.  They  are  usually  seen 
in  the  bottoms  of  valleys,  or,  at  some  contact  with  later  intrusive  rocks, 
which  have  turned  the  Cambrian  sedimentary  beds  upon  their  edges  so 
that  they  now  stand  nearly  vertically.  In  the  valleys  away  from  such 
contact,  they  are  found  to  dip  at  an  angle  of  from  40°  to  48°.  These 
rocks  invariably  contain  fossil  Hyolithes.  A  study  of  the  Cambrian  rocks 
leads  to  the  conclusion  that  this  region  was  not  coastal  at  the  opening  of 
the  Olenellus  Lower  Cambrian  epoch  as  these  fossiliferous  rocks  are  found 
in  the  bed  of  the  sea  as  far  out  as  Jeffrey's  bank  which  is  fifty  miles  from 
the  present  shore-line.  It  is  also  well  known  that  they  occur  beyond 
Cape  Sable  off  the  coast  of  Nova  Scotia. 

Peat  Deposits.  —  Deposits  of  peat  occur  in  nearly  every  town  in  the 
County  and  more  particularly  in  Danvers,  Middleton,  Topsfield,  Boxford, 
Georgetown,  and  Wenham.  From  a  careful  examination  it  is  estimated 
that  over  21,000  acres  of  peat  may  be  found  in  Essex  County  exclusive 
of  the  submerged  deposits  below  sea-water  at  high  tide.  The  great  Wen- 
ham  swamp  covers  an  area  of  some  two  thousand  acres,  nearly  all  of  which 
is  a  forest-grown  peat  deposit  from  nine  to  eleven  feet  in  thickness.  At 
the  Longham  basin,  an  artificial  feeder  of  Wenham  lake,  the  peat  was 
found  to  be  over  fifteen  feet  in  thickness.  The  deposits  surrounding  the 
ponds  at  Legg's  hill  are  eleven  feet  deep,  and  in  various  parts  of  the  County 
they  are  found  to  be  from  five  to  nine  feet  in  thickness.  If  this  peat  were 
made  into  coke  it  would  supply  fuel  of  excellent  quality  and  of  great 
value  for  domestic  use,  and  as  these  deposits  are  continually  being  formed, 
an  almost  inexhaustible  supply  is  always  available  for  local  use. 

Geological  Distribution  of  Plants.  —  Certain  plants  have  their  highest 
development  on  certain  kinds  of  soil  and  are  dependent  upon  the  chemical 
character  of  the  bed-rock  of  the  region  in  which  they  are  found  growing. 


Fig.    II.— CHESTNUT   TREES    (CASTANEA    AMERICANA!. 
Growing  upon  hornblende  granite  soil  on  the   Burley  farm,    Danvei 


Fig.    12.  — BEDDED    SLATES    AND    LIMESTONES    AT    EAST    POINT,    NAHANT. 


Fig,    13,  — HORNBLENDE    GRANITE    HEADLAND    AT    EASTERN    POINT,    GLOUCESTER, 


GEOLOGICAL    DISTRIBUTION    OF    PLANTS  39 

The  rock  formation  possessing  the  largest  percentage  of  silica,  with  an 
alkali,  potash,  alumina  feldspar,  such  as  the  hornblende  granite,  produces 
finer  specimens  of  certain  kinds  of  plants  than  will  grow  upon  rocks  hav- 
ing a  lime,  soda,  alumina  feldspar,  composition  such  as  the  hornblende 
dorite  or  the  augite  syenite.  The  latter  is  a  rock  with  a  low  silica  ratio, 
but  having  a  soda,  lime,  potash,  alumina  feldspar,  and  when  in  contact 
with  hornblende  granite,  it  is  difficult  to  distinguish  the  one  from  the 
other.  The  feldspars  in  the  two  rocks,  however,  are  chemically  quite 
distinct  and  a  marked  change  occurs  in  plants  growing  on  the  two  forma- 
tions, even  in  limited  areas  such  as  points  of  contact.  To  illustrate  — 
at  the  comer  of  Essex  and  Grapevine  streets.  East  Wenham,  on  the 
Rubbly  hills,  which  are  augite  syenite,  the  red  cedar,  Juniperus  Virgin- 
iana,  grows  equally  as  well  as  on  the  hornblende  diorite  areas  where  it 
has  its  greatest  development.  On  the  hornblende  granite  formation  at 
the  north  and  east  of  the  Rubbly  hill  area,  the  red  cedar  is  never  found 
growing. 

Lime  or  calcite  is  a  common  constituent  of  many  slates,  as  well  as  in 
the  diorite  rocks,  and  in  the  flora  of  lime-rock  soils  a  marked  change  is 
noticed  from  that  found  upon  rock  formations  that  are  rich  in  silica. 
This  is  also  true  of  alkali,  potash,  alumina  bed-rock,  whether  it  be  granite 
or  volcanic  aporhyolite.  The  common  rue  anemone,  Syndesmon  thalic- 
troides,  is  abundant  on  the  hornblende  diorite  slate  and  limestone  areas, 
but  it  is  rarely  found  growing  in  the  hornblende  granite  soils.  Anemone 
riparia  is  also  common  on  the  lime,  slate,  and  diorite  soils  in  Topsfield  and 
Boxford,  but  is  unknown  on  the  acid  hornblende  granite  soils.  Pink 
corydalis,  Corydalis  glauca,  is  a  common  plant  fotmd  growing  on  nearly  bare 
hornblende  granite  ledges,  but  it  is  unknown  on  the  diorite  or  limestone 
areas  in  the  County.  The  round-leaved  violet,  Viola  rotundifoUa,  is  occa- 
sionally found  growing  on  granite  areas,  but  never  on  the  diorites  or  lime- 
stones. The  tick-trefoils,  Desmodiuwi,  are  common  plants  in  the  woods 
on  the  augite  syenite,  diorite,  slate,  and  limestone  formations,  but  are 
very  rarely  found  on  the  granite  areas.  Dwarf  cherry,  Prunus  pumila, 
grows  abundantly  on  the  granite  soil  in  South  Peabody,  but  is  unknown 
on  syenite  or  diorite  soils.  The  three-toothed  cinquefoil,  Potentilla  tri- 
dentata,  may  be  seen  growing  in  the  granite  soil  at  Gloucester  and  Rock- 
port.  It  is  rare,  however,  in  the  syenite  soils  and  is  unknown  in  the 
diorite  areas. 

Bristly  sarsaparilla,  Aralia  hispida,  grows  in  great  abundance  in  the 
granite  soils,  but  is  rare  or  unknown  on  the  diorite  areas.     Red-berried 


40  GEOLOGICAL    DISTRIBUTION    OF    PLANTS 

elder,  Samhucus  puhens,  is  common  at  Gloucester  and  Rockport  on  granite, 
but  is  rare  on  syenite  and  unknown  on  the  diorite  areas.  The  blue-stemmed 
golden-rod,  Solidago  ccesia,  is  common  on  granite  and  aporhyolite  areas 
and  rare  on  diorite,  while  showy  golden-rod,  Solidago  speciosa,  is  common 
on  diorite  and  syenite  areas  and  rare  in  the  granite  regions.  The  yellow 
thistle,  Cnicus  horridulum,  is  common  at  Rockport  on  the  hornblende 
granite  and  imknown  on  the  diorite.  The  cowberry,  Vaccimum  vitis- 
idcea,  is  only  found  growing  on  diorite  and  slate  regions  in  Danvers  and 
Topsfield.  The  bearberry,  Arctostaphylos  uva-ursi,  is  common  in  the 
granite  soil  of  Peabody,  Beverly,  Manchester,  and  Rockport,  but  is  un- 
known in  the  diorite  or  lime-slate  localities.  Red  cedar,  Juniperus  Vir- 
giniana,  and  low  juniper,  Juniperus  communis,  are  both  very  common  on 
the  diorite,  augite  syenite,  and  lime-slate  areas  in  all  parts  of  the  County 
from  Saugus  to  Rockport,  and  northwesterly  to  Methuen,  but  the  first 
has  never  been  observed  upon  a  hornblende  granite  area.  Black  Ash, 
Fraxinus  sanibucifoUa;  white  cedar,  Chamcecyparis  spharoidea;  hobble- 
bush.  Viburnum,  lantanoides;  red  maple,  Acer  rubrum;  and  white  maple, 
Acer  dasycarpum,  all  grow  almost  exclusively  on  peat  and  river-silt 
soils  and  are  not  affected  by  bed-rock  soils.  Many  other  plants  are  com- 
mon to  one  kind  of  soil,  which  apparently  seems  due  to  the  chemical 
character  of  the  bed-rock. 


Fig.    14.— GAP    HEAD    AND    STRAITSMOUTH    ISLAND.    ROCKPORT. 
Showing  an  augite  syenite  contact  with   liornblende  granite. 


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Fig.    15.  — SQUAM    RIVER    FROM    WEST    GLOUCESTER. 
Showing  tidal   marshes. 


Fig.    16   —TIDAL    MARSH    AT    ROWLEY. 
View  from  the  railroad   at   high  tide;    Plum   island   in  the  distan 


Fig.    17.  — LAGOON    WEST    OF   JEFFREY'S    NECK,    IPSWICH. 
Showing  tidal   marsh  and  drumlins  in  the  distance. 


CHAPTER   II,. 

COAST-LINE  TOPOGRAPHY 

Rocky  Headlands.  —  The  bedded  sedimentary  slates  and  limestones  of 
East  point,  Nahant,  show  somewhat  rectangular  outlines  while  the  massive 
crystalline  igneous  intrusive  rocks  at  Little  Nahant,  and  elsewhere  on 
the  coast,  assume  particularly  rugged,  broken,  and  bizarre  forms  among 
which  are  rarely  seen  traces  of  the  rectangular  outlines  commonly  present 
on  shores  where  bedded  rocks  occur.     (See  Figs.  12,  13,  14.) 

The  general  tendency  of  marine  erosion  is  to  eventually  reduce  irregu- 
larities, cut  back  headlines,  and  fill  the  intervening  bays  with  silt.  Bars 
or  ridges  are  thus  formed  across  the  mouths  of  estuaries  and  other  notable 
indentations  of  the  land,  which  eventually  are  closed  more  or  less  com- 
pletely. Hence,  all  seacoasts,  which  can  be  shown  to  be  of  relatively 
great  age,  have  a  gently  sinuous  or  profusely  curved  outline,  and  con- 
versely, highly  indented  coasts  are  of  recent  origin,  for  the  sea  has  not  had 
sufficient  time  to  reduce  their  irregularities. 

Smooth  or  Regular  Coast-Lines.  —  These  may  be  high  and  steep  or  low 
and  gently  shelving,  the  one  kind  often  alternating  with  the  other.  In 
some  places  the  cliffs  project  boldly  beyond  the  average  coast-lines  and 
form  headlands ;  elsewhere,  they  curve  backwards,  or  their  continuity  may 
be  interrupted  by  more  or  less  numerous  creeks  or  small  inlets. 

When  the  joint  plains  of  the  bed-rock  of  the  shore  are  somewhat  reg- 
ular, as  in  the  slates,  limestones,  and  some  granites  and  basalts,  the  mural, 
or  wall-like  cliffs  may  appear;  while  where  diorite,  syenite,  and  the  crys- 
talline schists  form  the  bed-rocks  of  the  coast,  they  exhibit  every  variety 
of  form  except  the  rectangular.  From  Cape  Ann  northward  and  along 
the  coast-line  of  New  Hampshire  and  southern  Maine  the  shore  is  gently 
shelving  and  regular,  softly  sinuous  in  outline,  and  exhibits  a  succession 
of  broad,  evenly  curved  bays.  These  bays  are  separated  by  low  capes 
and  headlands,  broadened  by  banks  of  beach  sand,  sand-dunes,  and  beds 
of  gravel,  behind  which  appear  salt  or  brackish  water  lagoons  and  salt 
marshes.  These  lagoons  sometimes  take  the  form  of  shallow  deltas  ob- 
viously owing  their  origin  to  the  action  of  the  rivers  and  small  streams 

45 


46  DROWNED    RIVER    VALLEYS 

(see  Figs.  i6,  17),  but  the  drift  materials  carried  shoreward  by  waves 
and  tidal  currents  are  a  main  factor  in  filling  up  these  lagoons.  The 
drift  carried  to  the  sea  by  a  stream  does  not  always  accumulate  opposite 
its  mouth,  for  tidal  currents  often  prevent  the  rapid  growth  of  a  delta 
by  sweeping  away  much  of  the  drift  material  and  depositing  it  along  the 
shore.  This  is  especially  noticeable  at  the  mouth  of  the  Merrimac  river, 
at  Newburyport,  where  most  of  the  drift  brought  down  by  the  river  is 
deposited  on  Plum  island  to  form  off-shore  bars. 

Drowned  River  Valleys  Due  to  Subsidence.  —  Coastal  plains  are  the  re- 
sult of  crustal  movements  and  all  highly  indented  coast-lines  are  evidence 
that  the  land  is  being  submerged  and  is  consequently  sinking.  The  coast 
of  Essex  Coiinty  is  an  example,  which  is  further  shown  by  the  numerous 
drowned  stream  valleys,  the  tide-water  inlets,  and  the  peninsulas  and 
fringing  islands  which  abotmd  on  the  rocky  shores.  These  features  are 
especially  noticeable  from  Cape  Ann  southward  to  Chelsea  creek,  and  also 
extend  over  the  whole  Boston-Charles  river  area  and  southward  to  Cape 
Cod.  For  an  excellent  example  of  a  drowned  river  valley,  the  Parker 
river  below  the  dam  at  the  Bjrfield  woolen  mills  should  be  examined. 
(See  Figs.  18,  19.)  There  is  approximately  the  same  height  in  the  rise 
and  fall  of  the  tide  at  that  point  as  at  Plum  Island  sound,  nine  miles  from 
the  mouth  of  the  river.  The  tidal  marsh  at  Ipswich,  Rowley,  and  Saugus 
should  also  be  noted  as  exhibiting  a  drowned  topography  due  to  subsid- 
ence.    (See  Figs.  15,  20,  21.) 

Pltim  island  at  the  north  is  an  example  of  glacial  morainic  hills,  prob- 
ably a  series  of  drumlins,  that  are  very  nearly  base-levelled  by  sea  wave- 
action  due  to  subsidence.  The  bases  of  these  morainic  hills  reach  out  into 
deep  water.  Emerson's  rocks,  which  are  forty  to  sixty  yards  from  the 
present  shore  of  Pliun  island,  are  an  example  of  one  of  these  base-levelled 
drumlins.  Back  from  the  drumlins,  which  are  now  covered  with  Post- 
Pleistocene  wind-blown  sands  and  sand-dtmes,  lagoons  and  tidal  marshes 
have  formed,  reaching  westerly  to  Ipswich  and  Rowley  and  covering  a 
space  of  at  least  five  hundred  acres.  The  morainic  drift  boulder-till  of 
the  drumlins  was  foiTned  during  the  early  Glacial  period.  The  erosion  of 
this  boulder-till  by  marine  action  is  still  going  on,  as  a  visit  to  the  south- 
em  end  of  Pltim  island  at  high  tide  will  demonstrate,  for  the  tide-water 
is  turbid  with  clay  sediments  eroded  from  the  base  of  the  dnimlin  at 
the  "Bluffs."  This  must  be  caused  by  subsidence,  for  there  would  be 
marine  deposition  of  sand  and  gravel  at  the  base  of  the  "  Bluffs, "  if  eleva- 
tion were  going  on  at  present  instead  of  marine  wave-erosion. 


Fig.    18.  — PARKER    RIVER,    BELOW    THE    BYFIELD    WOOLEN    MILLS. 
At   low   tide. 


Fig.    19.— PARKER    RIVER    BELOW    THE    BYFIELD    WOOLEN    MILLS. 
At  high  tide. 


Fig.   20.  — SAUGUS    RIVER    MARSHES    AT    HIGH    TIDE. 
Showing  drowned  topography  due  to  subsidence, 


Fig.   21.  — SAUGUS    RIVER    MARSHES    AT    HIGH   TIDE. 
From  the   Lynn  and   Boston  turnpike,   looking  towards   Lynn. 


SUBSIDENCE  51 

The  numerous  islands  and  small  bays,  the  drowned  valleys  covered  by 
water  at  high  tide,  and  the  amount  of  land  surface  that  is  covered  by 
sea  water  at  high  tide,  39,788  acres,  all  indicate  that  the  area  covered 
by  the  Coimty  has  been  sinking.  Tide-water  flows  up  the  Merrimac 
river,  resulting  in  a  rise  and  fall  of  five  feet  at  Groveland  bridge,  sixteen 
miles  from  the  mouth  of  the  river.  At  the  dam  of  the  Byfield  Woolen 
Mills  on  the  Parker  river,  nine  miles  from  Plum  Island  sound,  there  is  a 
rise  of  eight  to  ten  feet.  The  Ipswich  river.  Plum  Island  river,  Squam 
river.  Castle  Neck  river,  and  Porter's,  Crane,  and  Waters'  rivers  at  Dan- 
vers,  are  all  typical  streams  or  drowned  valleys  in  which  the  water  flows 
out  at  low  tide.  (See  Figs.  15,  22,  23,  25.)  Chelsea  creek,  the  boiondary 
between  Essex  Coimty  and  Suffolk  County  on  the  south,  is  a  tide-water 
brook,  and  Saugus  river  is  another  example  of  the  drowned  valley.  These 
streams  all  illustrate  drowned  topography  in  a  youthful  stage  of  develop- 
ment. 

Subsidence.  —  Evidences  of  subsidence  are  clearly  shown  along  the 
entire  coast-line  in  many  sheltered  coves.  At  Nahant,  in  the  cove  be- 
tween Bass  point  and  the  steamboat  landing,  covered  by  thirteen  to  sbc- 
teen  feet  of  water  at  high  tide,  may  be  seen  numerous  stumps  of  several 
species  of  forest  trees.  Among  those  which  are  well  enough  preserved 
to  be  determined  are  white  pine,  swamp  or  white  cedar,  hemlock,  spruce, 
ash,  oak,  and  maple.  The  roots  of  these  trees  are  found  in  origin'al  leaf- 
mold  and  peat-beds,  from  one  to  three  feet  in  thickness,  which  rest  upon 
a  very  tenacious,  slippery,  blue  clay  of  unknown  depth,  the  leaf-mold  and 
peat-beds  being  covered  by  washed  sand  and  stones  of  all  sizes  in  a  stra- 
tum of  varying  thickness.  There  are  several  other  places  at  Nahant 
where  peat-beds  are  seen  at  or  near  low-water  mark.  (See  Fig.  27.)  One, 
in  the  southwest  cove  of  Crescent  beach,  is  quite  extensive  and  contains 
many  logs  and  stumps  of  old  forest  trees ;  another,  on  the  northwest  side 
of  Little  Nahant,  is  of  a  similar  character.  Lynn  harbor  and  the  marshes 
of  Saugus  furnish  niomerous  examples  of  old  peat-beds  in  which  large 
logs  of  pine  and  oak  lie  imbedded  below  the  recent  accumulation  of  marine 
peat  and  salt-grass  roots. 

On  the  Beverly  shore,  between  West's  beach  and  Misery  island,  are 
many  stumps  of  forest  trees  which  may  be  seen  at  low  tide,  when  the 
water  is  clear  and  still,  at  a  depth  of  twelve  or  fourteen  feet.  A  piece 
secured  from  one  of  these  stumps  proved  to  be  white  pine. 

In  a  cove  near  Chubb's  island,  Manchester,  at  a  depth  of  eleven  feet 
below  high-water  mark,  are  the  remains  of  an  oak  stump,  which,  now 


52  SUBSIDENCE 

divested  of  the  sap-wood,  is  twelve  feet  in  diameter  inside  the  buttresses, 
representing  the  tree  at  its  full  growth  in  this  region.  In  Manchester 
harbor,  inside  of  the  Ram  islands,  stumps  of  white  pine  and  oak  are 
found  in  the  original  leaf -mold  and  peat-beds  covered  by  washed  sand  and 
rocks  as  at  Nahant. 

On  Kettle  Cove  beach,  Manchester,  submerged  stumps  are  visible  at 
low  water  during  the  spring  tides.  Near  the  old  road-bed,  inside  of  Crow's 
island,  the  marine  peat  and  salt-grass  roots  are  from  ten  to  fourteen  inches 
in  thickness.  Directly  under  the  marine  peat  is  a  bed  of  leaf -mold  and 
fresh-water  peat  from  three  to  four  and  one-half  feet  in  thickness,  in 
which  are  foimd  numerous  logs  of  pine,  spruce,  and  white  cedar  and  the 
branches  of  the  ground  yew,  Taxus  Canadensis,  the  last  named  remaining 
in  its  normal  prostrate  position.  Below  the  peat  are  large  oak  stumps 
standing  in  the  glacial  drift  where  the  trees  formerly  grew.  While  secur- 
ing a  specimen  of  one  of  the  larger  oak  roots,  scratched  pebbles  and 
grooved  stones  were  found  with  oak  roots  growing  around  them  in  their 
natural  position.  From  these  observations  it  would  appear:  (i)  That 
the  ancient  oaks  grew  on  the  glacial-till  which  became  depressed;  (2)  that 
a  lake  formed  on  this  area  in  which  accumulated  the  peat  and  leaf -mold 
upon  which  grew  the  pine,  cedar,  spruce,  and  ground  yew;  (3)  that  this 
in  turn  became  submerged  and  the  marine  peat  and  salt-grass  formed 
above  it ;  (4)  and  lastly,  that  the  seaward  slope  has  become  so  great  that 
the  waves  are  cutting  into  and  carrying  away  these  earlier  formations  and 
thus  exposing  them  to  view. 

Red  cedar  stumps  have  been  found  at  Mingo  beach  some  of  which  are 
six  inches  in  diameter,  only  the  heart-wood  remaining.  With  these  were 
many  logs  of  spruce  and  hemlock  ramified  by  the  borings  and  containing 
shells  of  Petricola  phoUdiformis,  a  moUusk  abundant  in  the  peat  and  clay 
of  this  beach.  (See  Fig.  26.)  The  peat  at  this  point  is  five  and  one-half 
feet  in  thickness,  or  fourteen  and  one-half  feet  below  high  water  to  the 
bottom  of  the  peat  as  seen  on  the  beach.  In  this  peat  hundreds  of  wings 
of  water-beetles  and  a  great  many  fragments  of  other  insects  have  been 
found,  together  with  roots  of  the  cow  lily,  white  pine  cones,  oak  acorns, 
spruce  cones,  and  roots,  logs,  and  stumps  of  spruce,  hemlock,  pine,  and 
oak  mixed  in  great  confusion.  1 

Salem  harbor  furnishes  additional  evidence  of  subsidence,  and  sunken 
stumps  of  forest  trees  have  been  observed  at  Phillips'  and  King's  beaches 
in  Swampscott,  and  also  at  Marblehead  beach,  while  the  beaches  and 
marshes  of  Ipswich,  Rowley,  and  beyond  furnish  similar  deposits.     Speci- 


Fig.   22.  — WATERS    RIVER,    OANVERSPORT,    AT    LOW   TIDE 
Beverly  shore  in  the  distance. 


-CRANE    RIVER,    OANVERSPORT,    AT   NEARLY    LOV/   TIDE. 

Showing  the  meandering  of  the  stream. 


Fig.   24. —FOREST    RIVER,    SALEM,    AT    LOW    TIDE. 
Jeggles'   island   in  the  foreground  and    Legg's  hill   in  the  distance.     The  tide   rises   here  from  8  to  I  4  feet. 


Fig.    25  —FOREST    RIVER     SALEM,    ABOVE   THE    DAM,    AT    LOW    TIDE. 
From   Legg's  hill 


SUBSIDENCE  57 

mens  have  been  collected  from  the  stumps  in  many  of  the  places  referred 
to  above  and  may  be  seen  in  the  museum  of  the  Peabody  Academy  of 
Science  at  Salem. 

In  1894,  soundings  were  made  in  Salem  and  Marblehead  harbors  for 
the  purpose  of  comparing  the  depths  of  the  water  over  certain  rocks  with 
those  given  in  the  report  and  on  the  chart  prepared  by  Dr.  Nathaniel 
Bowditch  in  1804  and  1805.  Dr.  Bowditch  stated  that  the  stimmit  of 
Boden's  rock  was  seven  feet  below  low  water  on  the  full  and  change  of 
the  moon,  taken  from  easily  recognized  compass  points  on  the  mainland 
and  islands  in  the  harbor.  Soundings  taken  on  this  spot,  under  similar 
conditions,  July  17,  1894,  gave  nine  feet  of  water;  and  again,  August  i, 
1894,  gave  eight  and  one-half  feet  of  water.  These  soundings  were  made 
with  care,  and  offer  evidence  of  a  subsidence  in  the  past  ninety  years  of 
at  least  one  and  one-half  feet  at  this  point. 

Dr.  Bowditch's  report  gives  five  feet  of  water,  at  mean  low  water, 
on  the  summit  of  Privy  ledge,  three  himdred  yards  outside  Ome's  island. 
August  2,  1894,  there  was  seven  feet  of  water  at  this  point,  indicating  a 
subsidence  of  two  feet.  There  is,  however,  in  all  probability  a  greater 
amount  of  erosion  at  this  place  than  on  Boden's  rock  in  the  harbor.  Dr. 
Bowditch  reported  six  feet  of  water  on  the  shoalest  portion  of  Abbot's 
rock,  while  on  August  30,  1894,  eight  feet  of  water  was  found.  Taken  at 
low  water,  August  31,  1894,  Archer's  rock  had  eight  feet  of  water;  Septem- 
ber I,  1894,  Bowditch's  ledge  had  seven  and  one-half  feet;  and  Septem- 
ber 2,  1894,  Cut-throat  ledge  had  six  feet  of  water.  In  Dr.  Bowditch's 
report,  six  to  seven  feet  of  water  is  given  for  Archer's  rock,  which  is  one 
foot  less  than  appeared  in  1894;  Bowditch's  ledge  had  five  to  six  feet  of 
water  in  1804-5,  where  soimdings  in  1894  gave  seven  and  one-half  feet. 
On  Cut-throat  ledge,  Bowditch  gave  four  feet  of  water,  while  six  feet  was 
found  in  1894  at  extremely  low  water.  These  soundings  indicate  a  con- 
siderably greater  depth  of  water  on  all  of  these  ledges  than  existed  ninety 
years  ago.  This  also  agrees  with  the  estimate  of  Prof.  W.  J.  McGee  of 
two  feet  of  siibsidence  for  the  century  for  the  entire  coast.' 

From  aU  observations  made  the  evidence  points  to  the  conclusion  that 
there  has  been  a  subsidence  of  the  land  surface  of  the  coast  region  of 
Essex  Cotmty  in  recent,  or,  more  accurately  speaking,  in  Post-Terrace 
times,  and  that  this  subsidence  is  still  in  progress  is  clearly  indicated  by 

'  See  the  Forum,  Vol.  IX,  p.  448  ;  and  Bulletin  of  the  Essex  Institute,  Vol.  XXVI,  pp. 
64-73-    . 


58  SEA    BEACHES 

the  submerged  forest  growth  and  peat-beds  and  the  compared  soundings 
in  the  harbors. 

Sea  Beaches.  —  The  incoming  tides  and  littoral  currents  setting  shore- 
wards  from  the  north,  transport  sediments  of  sand,  mud,  and  silt  from 
shallow  parts  of  the  sea  bottom  and  from  along  the  shore.  These  sedi- 
ments are  the  result  of  wave-action  in  cutting  backward  the  headlands 
and  beaches  toward  the  northeast.  Such  action  is  now  going  on  at  Great 
Boar's  Head  and  Little  Boar's  Head  in  New  Hampshire,  and  on  the  gravel 
and  sand-banks  along  the  whole  shore  of  the  state  of  Maine.  Some  of 
these  sediments  are  no  doubt  from  off-shore  sources  and  are  brought  along 
by  the  Labrador  current  from  points  at  the  north  and  taken  shorewards 
by  tides  and  Kttoral  currents.  Heavy  easterly  gales  cause  breakers  of 
great  power  to  cut  into  exposed  ledges  and  islands,  as  may  be  seen  at  the 
Isles  of  Shoals,  where  the  waves  cut  into  and  remove  large  masses  of  rocks 
which  in  a  short  time  are  reduced  to  sand  and  mud  by  the  action  of  the 
sea.  This  helps  to  swell  the  volxune  of  sand  and  sediment  on  the  beaches 
of  the  mainland. 

SaHsbury  beach  derives  its  sand  from  this  source,  and  more  directly 
from  the  rocky  parts  of  the  shores  of  Seabrook  and  Hampton.  The  pre- 
vailing northerly  winds  drive  these  sands  and  sediments  southward  the 
length  of  the  beach  and  then  into  the  swiftly  flowing  tidal  currents  of 
the  Merrimac  river,  where  they  are  actually  ferried  across  its  mouth  on 
the  Newburyport  bar  or  delta  to  Plum  island.  This  delta  at  low  tide  is 
covered  by  only  a  few  feet  of  water,  and  over  it  the  tide  rushes  in  and 
out,  causing  numerous  eddying  currents  which  set  towards  the  shore  and 
carry  vast  quantities  of  sand  upon  the  island. 

Much  of  the  sediment  which  forms  the  delta  at  the  mouth  of  the  Merri- 
mac comes  down  the  river  from  below  the  Lawrence  dam.  During  the 
spring  floods,  the  river  cuts  into  its  banks  of  sand,  boulder-till,  and  gravel 
at  nearly  every  headland  between  Lawrence  and  Newburyport,  filling  the 
bed  of  the  river  and  forming  shoals  and  mud-banks,  which  are  constantly 
being  swept  onward  by  the  current  and  tidal  waters  to  the  delta  at  its 
mouth,  there  to  swell  the  vast  accumulation  of  sand  and  sediment  on 
the  sea  coast  and  on  Plum  island.  Large  amotmts  are  also  spread  out 
over  the  Joppa  flats  and  carried  down  Plum  Island  river  to  Pltim  Island 
sound,  Newbury,  and  Rowley. 

Plum  island  is  a  bar  off  the  shores  of  the  towns  of  Newbury,  Rowley, 
and  Ipswich.  It  is  about  eight  miles  in  length,  extending  from  Newbtiry- 
port  to  Ipswich   in    a  series  of  remnants  of  drumlins,  gravel-banks,  and 


Fig.   26.— MINGO    BEACH,    BEVERLY    (1894). 
Showing  submerged  peat-beds  and   logs  and  stumps  of  forest  tr( 


Fig.   27.  — POND    BEACH,    NAHANT    (1894). 
Showing   submerged  stumps  of  white  pine  trees. 


SEA    BEACHES  61 

ridges  of  boulders.  The  island  curves  slightly  to  the  southeast  on  the 
beach  side,  while  on  the  inshore  side  Plum  Island  river  cuts  its  channel 
through  the  salt  marsh  that  covers  the  old  lagoon  formed  inside  of  this 
bar.  The  greatest  width  of  the  island  is  about  one-half  of  a  mtle.  The 
sand-ridge  at  Rowley,  and  its  breaker  on  the  ocean  side  of  the  island, 
which  may  be  seen  at  low  water,  are  within  one  htindred  yards  of  the 
shore  (see  Fig.  28),  except  near  the  delta  at  the  mouth  of  the  Merrimac, 
where  the  island  and  its  shoals,  at  low  water,  are  nearly  a  mile  wide,  and 
also  at  the  southern  side  of  the  island,  at  Ipswich,  where  the  outer  break- 
ers are  over  five  hundred  yards  from  the  shore  and  beyond  Emerson's 
rocks.  Wind  storms  and  littoral  currents  are  continually  driving  the 
sand  and  finer  sediment  southward  along  the  shore  of  the  island  into 
Ipswich  bay  and  down  Plum  Island  river  into  Plum  Island  sound.  Off- 
shore ridges  are  then  formed,  on  which  the  sea  breaks,  and  the  undertow 
then  drives  the  sand  and  sediment  shoreward  upon  Ipswich  beach  and 
Castle  Neck.     (See  Fig.  29.) 

At  the  northern  end  of  Plum  island  and  opposite  the  Joppa  fiats,  as 
they  run  out  from  Woodbridge  island,  there  is  a  pond  called  "the  Basin," 
which  was  formed  by  the  Merrimac  and  its  tidal  waters,  by  cutting  into 
the  sandy  shores  of  the  island  while  running  out  through  the  narrow 
channel.  The  opening  into  "the  Basin"  is  dammed  across  by  a  looped 
bar  which  at  low  tide  produces  the  pond. 

Ipswich  beach  is  situated  on  the  shore  of  Ipswich  bay  between  Plum 
island  and  the  north  shores  of  Gloucester  and  Rockport,  and  is  formed  by 
an  indenture  of  the  coast-line  caused  by  the  cutting  away  and  removal 
by  streams  and  sea  wave-action  of  sedimentary  beds  of  slate  and  sand- 
stone. (See  Fig.  31.)  Remnants  of  these  bed-rocks  may  be  seen  on  the 
shore  at  "the  Loaf,"  which  is  at  the  northern  end  of  Cofifin's  beach.  West 
Gloucester  (see  Figs.  33,  34),  at  Conomo  point,  Essex,  and  on  the  old 
Ipswich  and  Essex  road. 

The  water  in  the  Ipswich  bay  is  shallow,  the  bottom  for  over  a  mile 
offshore  being  bare  at  low  tide  except  for  the  narrow  and  ever  changing 
ship  channel  leading  to  Plum  Island  sound  and  Ipswich  river.  This 
channel  is  deep,  and  the  sand  and  sediment  which  are  being  moved  south- 
ward along  the  coast  are  dropped  to  the  bottom  of  the  channel  and  there 
remain,  for  at  that  depth  there  is  not  sufficient  agitation  to  move  them. 
But  the  supply  of  drift-sand  brought  to  this  point  does  not  cease,  and  the 
natural  result  is  the  accumulation  of  a  sand-ridge  in  the  channel  which 
causes  it  to  move  to  one  side  or  the  other  as  the  current  cuts  a  new  pas- 


62  SAND-DUNES 

sage  with  the  least  possible  friction.  This  accounts  for  the  well-known 
shifting  of  this  channel.  The  United  States  Coast  Survey  Chart,  No. 
io8,  shows  such  a  shifting  of  this  channel  between  July,  1883,  and  July, 
1884.  This  sand-ridge  follows  the  boundary  between  the  deep  water 
near  the  channel  and  forms  a  spit  with  a  lagoon  shoreward.  At  the 
northern  end  of  the  beach,  at  a  point  opposite  Steep  hill,  such  a  spit  was 
built  up  during  the  seasons  of  1 900-1 902,  which  extended  southerly  over 
a  mile  in  a  line  parallel  with  the  beach  and  about  three  hundred  yards 
from  the  shore.  A  southeasterly  storm  forced  backward  the  sand  which 
was  drifting  down  the.  spit  and  carried  the  end  of  it  toward  the  shore, 
thereby  forming  a  true  sand-bar.  A  northeasterly  storm  then  demolished 
both  the  bar  and  the  sand-spit,  and  the  sand  and  other  sediment  filled 
the  lagoon  shoreward,  thus  extending  the  beach  to  an  outer  sand-ridge 
or  spit  and  nearly  to  deep  water.  (See  Fig.  30.)  Observations  cover- 
ing a  series  of  years  seem  to  prove  that  during  the  summer  months  the 
littoral  and  tide  currents  build  up  ridges  of  sand  and  drift  on  the  shallow 
bottom  parallel  with  the  beach,  so  that  in  a  favorable  season  there  may 
be  three  or  more  ridges  or  spits  of  sand  built  up  with  lagoons  behind 
them.  The  littoral  currents  transport  sediments  composed  of  sand,  mud, 
and  silt,  which  build  up  the  spits  and  bars,  and  as  the  proportions  of  these 
component  parts  vary,  so  varies,  in  all  gradations,  the  surface  of  the 
spit  and  the  resulting  beach,  from  hard  and  compact,  to  light  and  porous. 
Many  forms  of  corrosion,  erosion,  and  stream  adjustment  may  be  found 
here  during  a  season  to  illustrate  these  forms  in  detail,  as  well  as  examples 
of  spits,  bars,  ridges,  cuspated  forelands,  lagoons,  etc. 

Sand-Dunes.  —  Plum  island  is  covered  with  sand-dunes  and  drift- 
sands  that  are  continually  being  moved  southward  into  Ipswich  bay  by 
the  prevailing  high  winds  from  the  northwest  and  northeast.  Occasion- 
ally a  succession  of  heavy  easterly  gales  will  uncover  the  drumlins  at  the 
Ipswich  end  of  the  island,  known  as  "the  Jackman  farm,"  in  another 
season,  to  be  covered  again  by  the  ever-driftmg  sand  from  the 
northern  part  of  the  island.  This  wind-blown  drift-sand  is  washed 
upon  the  beach  by  incoming  tide-waters,  there  to  form  the  spits,  bars, 
and  ridges  of  Ipswich  beach  and  Castle  Neck.  During  the  winter  sea- 
son northeasterly  gales  and  high  tides  drive  into  Ipswich  bay  with  great 
violence  and,  forcing  the  sands  upon  the  beach,  level  and  destroy  existing 
forms  of  ridges,  spits,  and  bars.  Occasionally  heavy  northeasterly  gales 
of  several  days  duration,  will  chum  the  whole  bay  into  breakers  reach- 
ing out  from   the   shore,  line  upon  line,  for  a  distance  of  two  miles  or 


Seo.  Level 

^ 

Beach        _,.<r^ 
jujj  Lo-n  <^            1 

:;;??#■.;•.■■•.■.•  •'■  -.  • 

_^.- u  V .  V ,  ,'„..  • . . . •  r.-,- 

^^^. 

?>!.*>■  •  "."•"  .'■■-V.v.V-^-""  •••..'  •  •  '■•'■  ■■  •  ;  ,-■■•'" ;  J-  ■;  • ' 

WtMSiliiim 

Fig.    28.  — IDEAL    SECTION    OF    A    SEA    BEACH,    OF    WHICH    PLUM    ISLAND    BEACH    IS    A    TYPE. 


Sea,  Level 

Beo.ch 

.-.^^■:^^■^:v^ 

7<TT. 

■  j^ '•.•:••'..-..'.•.•.•  •v.v: 

■ 

ir:-r\^:'.\\- 

wiii^^, 

m 

Fig.   29.  — IDEAL    SECTION    OF    IPSWICH    BEACH. 


-THE    OFFSHORE    BAR    AT    IPSWICH    BEACH, 
Showing  cuspated  foreland  and  lagoon. 


-IPSWICH    BEACH    FROM    THE  TOP   OF   CASTLE    HILL. 
Showing  cuspated  foreland  and  offshore  bar. 


SAND-DUNES  67 

more.  The  undertow  from  these  breakers  dislodges  from  the  bottom  of 
the  bay  enormous  masses  of  sand  and  other  sediment  which  are  driven 
high  upon  the  beach  by  incoming  tides.  Sometimes  a  heavy  gale  will 
drive  the  wet  sand  over  Castle  Neck  five  hundred  yards  above  the  beach. 
Sand  thus  driven  upon  the  high  lands  soon  dries  and  is  then  blown  before 
the  wind  and  forms  sand-dunes.  (See  Fig.  35.)  Rarely  is  there  a  south 
wind  of  sufficient  force  to  drive  much  of  this  sand  northward  into  the 
bay,  and  therefore  its  tendency  is  to  accumulate  and  to  be  blown  south- 
ward. The  shore  currents  also  move  it  southward.  The  spit  reaching 
out  from  the  southeastern  part  of  Castle  Neck  shows  the  effect  produced. 
The  steep  bank  of  the  ship  channel  leading  into  the  mouth  of  Essex  river 
is  cut  through  a  delta  of  this  wind-blown  sand.  At  Ipswich  beach  the 
sands  encroach  upon  the  farm  lands  and  orchards  (see  Fig.  37),  and  the 
dunes  even  cover  the  drumlins  at  Castle  Neck,  southeast  of  which  lies  the 
Lakeman  farm,  which  has  been  entirely  covered  by  sand  and  the  attendant 
sand-dunes.     (See  Figs.  36,  38,  39,  42.) 

In  1898-9,  the  prevailing  northwesterly  winds  drove  the  sand-dunes 
down  to  the  end  of  Castle  Neck  opposite  the  entrance  of  Castle  river,  where 
new  banks  were  formed  forty  feet  in  height  which  extended  nearly  to 
the  Beacon  ledge  at  the  mouth  of  Castle  river.  Since  1901,  all  of  this 
great  mass  of  sand  has  been  removed  by  high  tides  and  northeasterly 
gales,  so  that  now  the  Beacon  ledge  is  two  hundred  yards  from  the  nearest 
sand-dunes.  These  northeasterly  gales  drive  the  sand  from  Castle  Neck 
southward  to  Coffin's  beach  and  inland  at  West  Gloucester.  A  large 
amount  of  sand  from  Plum  island  is  also  carried  up  the  Ipswich  river  by 
the  strong  tidal  currents  and  deposited  on  its  banks  in  the  vicinity  of 
Fox  creek  where,  for  over  a  century,  vessels  have  been  loaded  with  sand 
to  be  used  for  building  purposes  without  visibly  decreasing  the  amount 
deposited  at  this  point. 

Shore  dunes  of  considerable  number  occur  near  Coffin's  beach.  West 
Gloucester  (see  Fig.  34),  and  on  the  North  Shore  from  near  Halibut  point 
to  Annisquam.  The  latter  are  grassed  over,  showing  that  they  are  due 
to  conditions  not  in  operation  at  the  present  time.  Subsidence  of  the  land 
on  these  rocky  shores  causes  very  deep  water  so  that  only  small  amounts 
of  sand  are  scoured  up  from  the  rocks  and  deposited  on  the  shores.  On 
the  mainland  of  West  Gloucester,  opposite  Annisquam  village,  there  are 
very  extensive  dunes  which  are  in  active  operation,  moving  farther  inland 
each  year  (see  Figs.  40,  41),  and  several  tracts  of  tillage  land  have  been 
overwhelmed.     Dimes  now  cover  woodlands  in  this  region  to  a  depth  of 


68  EROSION    OF    THE    SHORE    BY    WAVE-ACTION 

eight  to  fifteen  feet,  the  sand  having  been  deposited  within  the  past  thirty- 
years.  Drift-sand  also  occurs  at  Rockport  in  the  valley  occupied  by  Cape 
Pond  brook,  near  the  Boston  and  Maine  railroad.  Here,  also,  it  is  wind- 
blown and  forms  small  dimes  which  are  now  fast  disappearing  as  the 
sand  is  blown  into  the  brook  and  carried  away.  These  sands  were  probably 
deposited  by  the  brook  in  times  of  flood. 

Erosion  of  the  Shore  by  Wave-Action.  —  The  north  shore  of  Gloucester 
from  Squam  lighthouse  to  Halibut  point,  Rockport,  is  bold  and  rocky, 
and  fringes  of  granite  and  dike-rock  ledges  are  exposed  for  nearly  the 
entire  distance.  In  a  small  bay  back  of  Davis'  Neck,  at  Bay  View,  sedi- 
ments of  sand  and  mud  are  deposited,  and  also  at  Folly  cove,  Lanesville, 
and  at  Plum  Cove  beach.  These  sediments  are  clearly  derived  from  till 
which  partially  covers  the  granite  ledges.  Sandy  Bay,  Rockport,  is  a 
deep  indentation  in  the  coast-line  formed  on  a  line  of  weakness  at  a  con- 
tact of  the  hornblende  granite  and  the  augite  syenite  rock  formations. 
At  the  deepest  part  of  the  bay,  the  incurving  shore  receives  the  larger 
portion  of  the  sediments  produced  by  wave-action  in  cutting  down  head- 
lands. On  the  eastern  side  of  Cape  Ann,  from  Emerson's  point  to  Cape 
Hedge,  there  is  now  a  cobblestone  beach.  The  sand  that  covered  this 
beach  in  1893,  has  been  dragged  into  deep  water,  carried  southward,  and 
deposited  on  Long]beach,  at  Gloucester,  from  thence  to  be  washed  along 
the  shore,  for  at  the  present  time  there  is  less  sand  upon  this  beach  than 
appeared  a  few  years  ago.  The  same  may  be  said  of  the  beach  between 
Brier  Neck  and  Bass  Rocks,  at  East  Gloucester.  Singing  Sand  beach  or 
Old  Town  beach,  at  Manchester,  is  also  wasting  away.  The  beach  de- 
rives its  name  from  the  rasping  sound  produced  by  the  sand  when  it  is 
walked  upon.  This  sand  is  peculiar  to  this  beach  and  the  sound  is  caused 
by  hard  mineral  surfaces  rubbing  against  other  projecting  surfaces.  A 
microscopical  study  of  sections  of  this  sand  has  demonstrated  that  a  por- 
tion of  the  grains  have  rutile  needles  in  and  through  the  quartz  and  stand- 
ing out  beyond  the  surface.  In  one  section  these  rutile  crystals  were 
found  to  radiate  like  the  spokes  of  a  wheel.  Zircon  crystals  are  also  pres- 
ent in  the  feldspars.  As  the  rutile  and  zircon  crystals  are  harder  and 
tougher  than  the  feldspars,  the  grinding  together  of  these  grains  pro- 
duces the  sound  which  gives  its  name  to  the  beach. 

Opposite  the  Ipswich  end  of  Plum  island  and  between  Ipswich  river 
and  Green's  creek  are  the  drumlins  known  as  Jeffrey's  Neck.  Between 
the  North  ridge  and  Plover  hill,  the  sea  has  cut  a  small  bay  at  the  mouth 
of  which  a  sand-bar  has  formed,  damming  the  opening  into  the  bay  and 


Fig.    32.— VIEW    FROM    GALE'S    POINT,    MANCHESTER,    AT    LOW    TIDE. 
Showing  the   following  islands:    House,    Misery,    Ram,    Baker's,    Eagle,   and    Lowell. 


Fig.  33.  — COFFIN'S    BEACH,    WEST   GLOUCESTER,   FROM    BLACK    ROCKS   TO   THE    LOAF. 
Showing  ripple  marks  and  cuspated  drifting  of  sand.      Ipswich  beach  and   Plum   island   in  the  distance. 


Fig.    34.  — COFFIN'S    BEACH,    WEST    GLOUCESTER. 

Showing  sand-dunes  and    Post- Pleistocene  or  Quaternary  drift  sand. 


I'K-' 

dl 

^tf^^ 

w 

■s^'^^^^.  ^  •     ■■<i~. 

Fig,    35.  — POST-PLEISTOCENE    WIND-BLOWN    SAND-DUNE    AT    CASTLE    NECK,    IPSWICH, 

Showing  stratification  of  the  sand. 


Fig.   36.  — IDEAL    CROSS-SECTION    FROM    HOG    ISLAND,    ESSEX,    TO    IPSWICH    BEACH. 
A.    Drumlin.      B.    Kame  gravel.      C.   Clay.      D.    Sand-dunes.      E.    Ipswich   Beach. 


Fig.   37.— POST-PLEISTOCENE    WIND-BLOWN    SAND    OVERWHELMING    AN    APPLE    ORCHARD. 
On  the   Lakeman  farm,   Castle   Neck,    Ipswich. 


EROSION    OF    THE    SHORE    BY    WAVE-ACTION  75 

making  what  is  now  known  as  Clark's  pond.  A  similar  bar  tmites  Great 
Neck  and  Little  Neck  at  Ipswich.  Davis'  Neck  is  connected  with  Bay- 
View,  Gloucester,  by  a  sand-bar,  and  a  sand-  and  cobblestone-bar  at  Brace's 
cove,  East  Gloucester,  encloses  Niles  pond.  Forty  years  ago.  Graves' 
island  was  connected  with  the  mainland  at  Manchester,  but  subsidence  and 
high  tides  have  cut  the  bar  and  it  has  now  entirely  disappeared.  Incipient 
bars  have  formed  in  the  comparatively  smooth  water  on  the  westerly 
side  of  Eagle,  Coney,  and  Misery  islands,  in  Salem  harbor,  and  a  few  years 
ago  Great  Misery  was  connected  with  Little  Misery  by  such  a  sand-bar, 
but  in  1 90 1  the  sea  had  cut  a  deep-water  channel  between  the  islands. 
Marblehead  Neck  is  tied  to  the  mainland  by  a  sand  and  cobblestone  beach 
(see  Fig.  43),  and  Nahant  is  connected  with  Little  Nahant  by  a  curved 
sand-bar,  and  beyond,  with  the  mainland  at  Lynn,  by  a  sand-bar  that  is 
over  a  mile  in  length.  A  small  bar  at  Pond  beach,  Bass  Point,  Nahant, 
encloses  Bear  pond.  The  long  bar  connecting  Little  Nahant  with  Lynn 
and  all  similar  bars  are  called  "tombolas,"  by  Italian  geologists.^ 

Nearly  all  of  these  bars  would  be  swept  away  by  the  sea  but  for  the 
work  of  man  in  repairing  the  waste.  The  sea  has  frequently  cut  a  pas- 
sage through  the  bar  connecting  Marblehead  Neck  with  the  mainland, 
and  the  beach  if  not  repaired  would  soon  open  up  a  channel  and  cause 
Marblehead  Neck  to  become  an  island.  The  same  is  true  of  Nahant  beach 
bar. 

'  See  F.  P.  Gulliver,  Proceedings  of  A.  A.  A.  Science,  1S99. 


CHAPTER   III 

OUTCROPS   OF    BED-ROCK 

Nearly  one  half  of  the  bed-rock  of  Essex  County  is  distinctly  strat- 
ified, and  by  means  of  our  knowledge  of  these  groups  the  geologic  age  of 
all  the  other  rock-masses  may  be  approximated.  The  term  "  stratified 
rock"  is  applied  to  different  rock-formations  in  which  stratification  is 
the  only  common  character,  and  although  the  syenites,  diorites,  felsites, 
and  some  of  the  breccias  show  stratification  in  part,  there  is  little  diffi- 
culty in  separating  them  from  the  limestones,  quartzites,  and  argillaceous 
rocks. 

Stratified  Rocks  of  Sedimentary  Origin.  —  The  sedimentary  rocks  of 
the  County  are  nearly  all  of  the  Olenellus  Lower  Cambrian  age,  and  are 
divided  into  several  groups:  the  slates,  sandstones,  limestones,  and  the 
quartzites,  all  of  detrital  origin  and  to  be  classed  as  more  or  less 
metamorphic. 

Metamorphism  is  here  used  in  a  broad  sense  as  indicating  the  produc- 
tion of  new  minerals  or  new  structuresi  or  both,  in  pre-existing  rock- 
masses.  An  excellent  example  of  thermal  metamorphism,  due  to  the 
intrusion  of  volcanic  rhyolite  rocks,  may  be  seen  on  the  Breakheart  Hill 
farm  in  Saugus.  The  slates  here  must  have  contained  a  considerable 
amount  of  carbonaceous  matter,  probably  due  to  animal  remains,  which, 
when  brought  into  contact  with  the  great  heat  of  the  intruding  rhyolites, 
were  transformed  into  graphite  and  produced  the  knotted-schists  or 
knottinschieffer  of  this  area.  These  slates  are  in  part  brecciated  by  the 
intrusion  of  veins  and  masses  of  the  rhyolite  rock,  and  in  some  parts  of 
the  slate-beds  the  metamorphism  assumes  the  type  of  flaky-schists,  with 
all  the  varying  gradations  between  knotted  and  flaky  forms.  The  slates 
and  sandstones  on  Marblehead  Neck  have  been  metamorphosed  by  the 
intrusion  of  veins  and  masses  of  hornblende  granite,  diabase  dikes,  and 
felsitic  porhyries.  The  carbonaceous  matter  has  been  transformed  into 
garnets,  and  the  slates  and  sandstones  have  been  changed  into  beds  of 
quartzite  and  mica-schist.     At  Nahant  the  Cambrian  slates  have  become 


-SAND    SPIT    OFF    CASTLE    NECK,   IPSWICH. 

from    Hog  island,    looking  across   Castle  river. 


-CONTINUATION    OF  THE    SAND    SPIT  OFF    CASTLE    NECK,   IPSWICH, 
seen  from   Hog  island.     Glacial  drift  boulders  appear  in  the  foreground. 


Fig.   40    —  SAND-DUNES    ON    A    ROCKY    HEADLAND    NEAR    COFFIN'S    BEACH. 
West  Gloucester. 


Fig.   41.  —  SAND-DUNES    SOUTH    OF    COFFIN'S    BEACH. 
West  Gloucester. 


Fig.   42.—  KAME    RIDGE   ON    SOUTH    BANK    OF    CASTLE    RIVER. 
North  of   Hog  island,    Essex.      Ipswich   lighthouse  and    Plum   island   in   the  distance  at  the  left. 


Fig.  43.— BARRIER    BEACH    BETWEEN    CLIFTON    AND    MARBLEHEAD   NECK. 
(July,    1905)  showing  sea-worn   pebbles  washed  into  windrows  by  the  tides. 


CAMBRIAN    ROCKS  83 

calcined  into  a  form  of  lydite,  and  andalusite  has  been  developed  in  the 
folia  or  bedding-planes. 

Cambrian  Rocks.  • —  The  Cambrian  rocks  of  Essex  Coimty  are  small 
remnants  of  a  series  of  folds  which  must  have  been  at  least  10,000  feet  in 
thickness.  These  remnants  are  now  seen  at  Pickering's  point,  South 
Salem,  on  the  shore  at  a  point  northeast  of  Fort  Pickering;  at  Naugus 
head  on  the  Marblehead  side  of  Salem  harbor;  and  northwesterly  across 
Beverly  harbor  at  the  base  of  Goat  hill.  As  the  inclination  or  dip  of  these 
strata  of  Cambrian  rocks  is  constant,  it  being  about  40°  southeast,  the 
distance  in  a  straight  line  across  the  upturned  remnants,  from  Naugus 
head  on  the  Marblehead  shore  to  the  outcrop  at  the  base  of  Goat  hill  in 
Beverly,  is  about  10,000  feet.  These  beds  probably  were  continuous 
across  the  area  now  known  as  Salem  and  Beveriy  harbors,  and  formed  a 
fold  at  least  10,000  feet  in  thickness,  covering  not  only  Salem  and  Beverly 
but  the  whole  of  Essex  County.  During  the  Cambrian  period  there  were 
mountains  of  these  strata  over  the  igneous  eruptive  granites  and  diorites. 
A  demonstration  of  the  above  conclusion  was  shown  at  the  time  an  arte- 
sian well  was  sunk  on  the  property  of  the  Salem  Electric  Lighting  Company, 
on  Peabody  street,  Salem.  This  well  was  bored  to  a  depth  of  four  hun- 
dred feet  through  nepheline  syenite  and  diabase  dike  rocks.  A  sufficient 
supply  of  water  not  having  been  reached,  it  was  decided  to  explode  a 
heavy  charge  of  dynamite  at  the  bottom  of  the  well.  The  explosion 
brought  to  the  surface  pieces  of  Cambrian  limestone,  one  containing 
fragments  of  HyoUthes.  By  the  accompanying  diagram  (see  Fig.  44)  it 
will  be  seen  that  this  well  is  about  5,400  feet  from  Naugus  head.  A 
similar  diagram  carrying  these  strata  to  the  outcrop  at  the  foot  of  Goat 
hill  in  Beverly,  would  demonstrate  the  strata  to  be  at  least  10,000  feet  in 
thickness. 

Half-tide  rock  and  Jeggles'  island,  in  the  southwestern  part  of  Salem 
harbor,  are  small  masses  of  the  harder  diorite  rock  which  cut  through 
the  Cambrian  slates.  Half -tide  rock  has  a  vein  of  syenite  cutting  through 
it.  The  harbor  itself  is  carved  out  of  the  softer  Cambrian  rocks,  especially 
those  near  the  contact  of  the  igneous  eruptive  rocks.  At  such  contacts 
invariably  there  is  deeper  water  than  elsewhere  in  the  harbor. 

At  Jeffrey's  ledge,  about  twenty  miles  east-northeast  from  Cape  Ann, 
a  deposit  of  Cambrian  rock  has  been  located,  containing  numerous  fossils 
of  HyoUthes  and  Stenotheca,  and  thereby  this  outcrop  may  be  connected 
with  the  Olnellus  Cambrian  deposits  of  Nahant.  Other  outcrops  of  these 
crystalline  Cambrian  sediments  have  been  found  in  various  parts  of  the 


84  CAMBRIAN    ROCKS' 

County.  One  at  Rowley,  chiefly  in  the  valley  between  Hunslow  hill  and 
Long  hill  but  occasionally  rising  to  an  elevation  of  one  hundred  feet, 
is  composed  of  a  series  of  schistose  argillite  shales,  ferruginous  sandstones, 
and  a  cherty  limestone  which  is  much  metamorphosed  in  bands  of  light 
and  dark  color.  Microscopical  examination  shows  this  limestone  to  be 
composed  of  plainly  stratified  sediments  of  calcite,  quartz  grains,  epidote, 
chlorite,  some  magnetite  and  limonite,  and  to  be  of  the  same  character 
as  that  at  Mill  cove.  North  Weymouth.  The  fossils  found  at  this  outcrop, 
which  can  be  identified,  are  all  in  the  cherty  limestone.  The  strike  of 
this  deposit  is  20°  north  of  east  to  southwest,  dip  40°  west,  which  is  nearly 
parallel  to  the  strike  of  the  Olenellus  Cambrian  deposit  at  Nahant  head. 
Another  outcrop  of  these  Cambrian  rocks  is  found  at  Topsfield  and  is 
composed  of  the  same  succession  of  schistose  argillite  shales,  ferruginous 
sandstone,  and  a  cherty  limestone  that  is  near  lydite.  Other  outcrops 
have  been  found  at  Archelaus  hill  in  West  Newbury,  at  an  elevation  of 
nearly  two  hundred  feet ;  in  red  argillite  shales  in  the  bed  of  the  Merri- 
mac  river;  at  Ward's  hill  in  Bradford;  and  on  the  high  hills  of  Methuen, 
at  an  elevation  of  one  hundred  feet. 

The  inference  to  be  drawn  in  explanation  of  the  presence  of  these 
Cambrian  deposits  scattered  over  the  County  is,  that  during  the  Cambrian 
period  there  was  a  vast  sheet  of  these  sediments  deposited  over  the  entire 
region  to  the  depth  of  some  htmdreds  of  feet;  but  the  great  amount  of 
denudation  from  various  causes,  particularly  through  the  agency  of  the 
ice-sheet  which  covered  this  region  during  the  Glacial  period,  together 
with  the  frequent  faulting  of  the  strata,  makes  it  nearly  impossible  to  give 
the  exact  depth  of  these  beds.  They  have  been  distorted  and  crumpled 
into  anticlinal  and  synclinal  folds  accompanied  by,  and  perhaps  casually 
connected  with,  the  intrusion  of  the  granite,  diorite,  syenite,  and  felsite 
eruptive  rocks.  The  eteolite-syenite  of  Naugus  head,  on  the  Marblehead 
shore,  and  at  Woodbury's  point,  on  the  Beverly  shore,  are  seen  to  cut 
these  sediments,  and  being  also  later  cut  by  gabbros  and  quartz  felsites, 
the  contact  metamorphism  is  so  complete  that  the  old  crystalline  sedi- 
ments are  now  found  as  mica-schists.  The  diorite  areas  of  Marblehead 
proper,  Salem,  Danvers,  and  Ipswich  often  contain  fragments  and  masses 
of  these  metamorphosed  crystalline  sediments.  At  Danvers  Centre  a 
granitic  gneiss  is  found.  In  Putnamville  and  Wenham  the  entire  area 
is  amphibolite  schist  or  foliated  hornblende  diorite.  Mining  shafts  and 
trenches  for  water-mains  have  opened  these  rock-masses  in  several  places, 
showing  the  actual  contact.     In  digging  a  well  at  Tapleyville,  Danvers, 


Fig.  45.— HORNBLENDE     EPIDOTE    GNEISS    CUT    BY    A    COARSE    HORNBLENDE    GRANITE. 
Crooked    pond,    Boxford. 


Fig.   46.— INCLUSION    OF    HORNBLENDE    EPIDOTE    GNEISS    IN    FOLIATED    QUARTZ    HORNBLENDE 

DIORITE. 
narrow   vein  of   the  diorite  cuts  through  the  gneiss  upon  which  the  watch  is  resting.     Southeast  of  Crool<ed   pond, 

Boxford. 


CAMBRIAN    ROCKS  '  89 

on  the  bank  of  Tapley's  brook,  a  bed  of  typical  argillaceous  shale  was 
revealed.  This  brook  occupies  the  valley  between  the  granite  areas  of 
Peabody  on  the  south,  and  the  main  mass  of  the  diorite  on  the  west 
and  north,  and  the  contact  of  these  eruptive  rocks  with  the  crystalline 
sediments  is  probably  so  distant  that  the  metamorphism  in  them  is  less 
complete. 

In  the  eruptive  dome-shaped  bosses  of  the  hornblende  granite  areas 
of  Saugus,  Lynnfield,  Peabody,  Manchester,  and  Cape  Ann,  there  are 
numerous  fragments  and  masses  of  these  metamorphosed  crystalHne 
sediments.  At  Saugus  on  the  east,  and  at  Lynnfield  on  the  west,  of  the 
granite  there  are  extensive  outcrops  which  are  seen  to  be  interstratified 
with  layers  of  quartzite  and  mica-schist.  This  mica-schist  is  identical, 
macroscopically  and  microscopically,  with  the  metamorphosed  argillites 
of  Nahant  and  Flying  point,  Marblehead  Neck.  The  strike  of  all  these 
beds  is  northeast  to  southwest,  varying  only  a  few  degrees  either  to  the 
north  or  east)  thus  showing  that  the  intrusion  of  the  eruptive  magma  was 
parallel  to  the  foliation  of  the  sedimentary  beds.  On  Cape  Ann  there 
are  numerous  masses  and  fragments  of  the  metamorphosed  sediments  in 
the  hornblende  granite.  One  large  mass,  near  the  Loaf,  a  rocky  point  on 
the  northern  end  of  Coffin's  beach.  West  Gloucester,  is  several  rods  in 
extent  and  the  foliation  shows  the  strike  to  be  northeast  to  southwest. 
This  outcrop  is  below  the  high-water  line  and  therefore  the  dip  cannot 
well  be  made  out.  Another  outcrop  near  Halibut  point  on  the  east  side 
of  Cape  Ann,  is  of  the  same  type  and  has  the  same  strike,  with  the  dip 
40°  west,  parallel  to  the  Cambrian  beds  at  Rowley  and  Nahant.  The 
position  of  these  two  metamorphosed  crystalline  sedimentary  beds  signifies 
that  they  are  remnants  of  an  anticlinal  fold  of  the  Cambrian  sediments, 
perhaps  produced  by  the  intrusion  of  the  eruptive  granite  magma  from 
beneath  them.  It  is  not  unreasonable  to  presume  that  the  granite  magma 
melted  and  enclosed  large  masses  and  fragments  of  these  old  Cambrian 
sediments,  metamorphosing  them  into  hornblende  and  mica-schist.  This 
theory  will  also  explain  the  presence  of  several  gneissic  fragments  found 
in  the  granite  quarries.  Such  a  mass  in  the  Trumbull  quarry  at  West 
Gloucester,  is  twenty  feet  in  length  and  tapers  to  a  point  near  the  surface 
of  the  dome-shaped  granite  boss.  The  enormous  force  exerted  by  the 
intrusion  of  the  granite  magma  from  beneath  upon  these  Cambrian  beds 
must  have  distorted  them  and  left  their  entire  surface  a  series  of  faults, 
cracks,  and  crevices,  thus  exposing  them  to  all  the  various  forces  of  erosion 
and  decay.     The  work  of  the  ice-sheet  during  the  Glacial  period  must 


90  HORNBLENDE    EPIDOTE    GNEISS 

necessarily  have  been  upon  these  sedimentary  beds,  scouring  and  grinding 
them  to  rounded  boulders  and  to  fine  till,  which  were  deposited  all  over 
Cape  Ann  and  in  the  waters  of  the  Atlantic.  One  of  these  stratified 
boulders  on  Ten  Pound  island,  in  Gloucester  harbor,  and  another  on 
Thatcher's  island,  are  typical  examples  of  the  larger  of  these  fragments, 
while  in  Whale  cove  there  are  great  numbers  of  all  sizes  and  of  every 
shape.  This  theory  would  also  account  for  the  absence  of  glacial  grooves 
and  striae  on  much  of  the  surface  of  the  granite  areas,  for  probably  the 
ice-sheet  never  touched  the  larger  portion  of  the  granite.  Aerial  decay 
has  since  destroyed  all  that  was  left  of  these  sedimentary  beds  after  the 
ice  period,  except  such  remnants  as  are  fotuid  to-day. 

A  large  number  of  thin  sections  from  all  the  outcrops,  when  studied 
with  the  microscope  to  determine  the  detrital  character  of  these  strati- 
fied beds,  have  invariably  sustained  the  determinations  made  in  the 
field. 

Hornblende  Epidote  Gneiss.  —  This  is  an  ancient  rock-mass,  and 
probably  the  oldest  member  of  the  Archean  series  represented  in  Essex 
County.  The  granitic  quartz  hornblende  diorite,  which  is  the  principal 
formation  in  the  Crooked  pond  area  at  Boxford,  and  which  occurs  in  both 
massive  and  foliated  forms,  cuts  through  the  hornblende  epidote  gneiss. 
Veins  of  granite  also  cut  both  of  these  rocks  in  various  directions.  (See  Fig. 
45.)  Nearly  half  a  mile  south  from  the  above  outcrop,  are  ntimerous blocks 
of  this  gneiss  as  inclusions  in  the  foliated  and  massive  quartz  hornblende 
diorite.  (See  Fig.  46.)  The  hornblende  epidote  gneiss  is  therefore  shown 
to  be  an  older  formation  than  the  quartz  diorite,  and  it  is  also  demon- 
strated that  the  flow  of  the  quartz  hornblende  diorite  magma,  which  picked 
up  the  blocks  of  this  gneiss,  was  from  the  north  in  a  southerly  course,  as 
there  are  no  outcrops  of  the  gneiss  south  of  the  included  blocks.  A  short 
distance  southwesterly  from  Crooked  pond  is  an  outcrop  of  this  rock  in 
the  form  of  a  conglomerate,  a  breccia  cut  by  forms  of  the  quartz  horn- 
blende diorite.  Dynamic  metamorphism  has  greatly  altered  the  minerals 
in  this  rock,  which  has  been  pressed  and  crushed  between  a  massive 
amygdaloidal  melaphyre  dike  on  the  east  and  the  quartz  hornblende 
diorite  on  the  west.  In  consequence,  the  augite  is  nearly  aU  replaced 
by  green  hornblende  which  the  crushing  force  exerted  was  sufficient  to 
thoroughly  metamorphose.  The  original  brown  hornblende  is  replaced 
by  biotite  and  the  soda-lime  feldspars,  and  the  soda-bearing  silicates 
are  separated  in  the  form  of  crystals  of  albite,  while  the  lime-bearing 
silicates,  in  conjunction  with  other  constituents  of  the  rock,  aid  in  forming 


Fig.   47.— PHOTOMICROGRAPH    OF    HORNBLENDE     EPIDOTE    GNEISS. 
Crooked   pond,    Boxford. 


-CAVE    IN    LEDGE    OF   QUARTZ    HORNBLENDE    DIORITE. 
East  of  Crooked   pond,  Boxford. 


HORNBLENDE    EPIDOTE    GNEISS  93 

the  minerals  rich  in  lime,  such  as  epidote,  zoisite,  and  calcite.  These 
minerals  form  narrow  elongated  lenses,  some  of  which  are  three  or  four 
inches  long  and  give  the  metamorphosed  rock-mass  a  distinctly  gneissic 
appearance,  suggesting  to  some  geologists  the  name  —  stratified  diorite. 
A  later  phase  of  the  metamorphism  of  this  rock  is  the  crushed  and  broken 
crystals  of  secondary  feldspar,  which  may  be  seen  near  the  contact  of  the 
aplitic  granite  veins,  which  cut  through  this  entire  series  of  melaphyre, 
quartz  diorite,  and  hornblende  epidote  gneiss.  North  of  Crooked  pond 
this  gneiss  has  been  quarried  for  building  purposes.  Southwest  of  the 
quarry  there  is  an  outcrop  of  this  rock  in  the  form  of  a  conglomerate 
of  rounded  pebbles,  which  becomes  a  breccia  still  further  in  the  same 
direction. 

South  of  Woodchuck  hill,  on  the  north  side  of  Boston  brook,  there 
is  an  outcrop  of  the  hornblende  epidote  gneiss  with  a  strike  northeast 
to  southwest.  Continuing  in  this  course  about  two  miles,  the  rock  again 
appears  on  the  Jenkins  farm  in  Andover.  Northeast  from  the  first  out- 
crop, it  is  also  seen  south  of  Fish  brook,  near  the  North  Andover  and  Box- 
ford  town  lines.  South  of  Kimball  and  Sawyer's  mill-pond  in  Boxford,  a 
series  of  outcrops  extend  nearly  to  Four  Mile  pond,  and  west  of  the  first- 
named  pond  a  gneissic  quartz  diorite  is  found.  On  both  sides  of  the 
outlet  to  Stiles'  pond,  and  on  either  side  of  Spofford's  pond,  are  outcrops 
of  hornblende  epidote  gneiss.  Southwest  of  Rock  pond  in  Georgetown, 
there  are  three  outcrops. 

On  the  bank  of  Mill  river,  at  Dodge's  mill,  Rowley,  this  formation 
appears,  and  in  a  northeasterly  direction  there  are  numerous  outcrops. 
Two  hundred  yards  southwest  from  the  Mill  river  outcrops,  a  blue  lime- 
stone appears,  beyond  which  is  another  outcrop  of  the  gneiss,  and  then  an 
outcrop  of  foliated  quartz  hornblende  diorite. 

On  the  south  side  of  Uptack  hill  in  Groveland  and  extending  eastward 
to  "Federal  City,"  are  several  outcrops  of  hornblende  epidote  gneiss, 
which  reach  southward  and  appear  on  both  sides  of  Rock  pond  in  George- 
town. Half  a  mile  north  of  Bald  Pate  pond  is  another  outcrop  in  a  rail- 
road cutting,  and  at  the  southeastern  base  of  Long  hill,  at  "Rooty  Plain," 
are  two  other  outcrops  between  which  appear  blue  limestone  and  quartzite. 
The  strike  of  the  whole  series  is  north  40°  east,  the  dip  varying  from  30° 
north  of  west  to  90°. 

Following  the  strike  of  the  hornblende  epidote  gneisses  across  Essex 
Cotmty,  there  are  outcrops  in  various  places  near  Foster's  pond,  Andover, 
and  on  the  roadside,  in  a  cutting  near  the  John  Jenkins  farm,  there  is  an 


94  ANCIENT    ROCKS    OF    SEDIMENTARY    ORIGIN    ON    CAPE    ANN 

exceptionally  good  exposure  where  this  gneiss  is  seen  for  several  rods 
with  the  same  strike  and  with  the  dip  slightly  to  the  west.  Numerous 
exposures  are  also  seen  in  Famhamville,  North  Andover,  and  on  the  Lacy 
farm  on  the  road  to  East  Boxford. 

Hornblende  epidote  gneiss  from  Crooked  pond  (see  Fig.  47);  section  across 
the  bedding,  microscopic  structure:  green  hornblende;  twinned  feldspar  with  numer- 
ous inclusions  of  quartz  grains;  patches  of  quartz  in  which  there  are  numerous 
fluid  inclusions;  large  patches  of  zoisite,  biotite,  and  magnetite;  numerous  areas  of 
chlorite  and  epidote.  Section  parallel  to  the  bedding  shows  the  zoisite  surround- 
ing hornblende  crystals  and  the  hornblende  in  turn  surrounding  grains  of  magnetite, 
all  lying  in  one  plane  across  the  section  dependent  upon  one  plane  of  pressure. 
Titanic  iron  surrounded  with  leucoxene  is  abundant  in  this  section. 

A  section  across  the  bedding  of  a  specimen  of  metamorphic  hornblende  epidote 
gneiss  from  the  John  Jenkins  farm,  Andover,  gave  brown  hornblende  allied  to 
green  hornblende  ;  magnetite  ;  plagioclase  with  numerous  inclusions  of  quartz  ; 
biotite  flakes,  and  masses  in  the  plane  of  bedding  ;  numerous  quartz  grains,  many 
of  them  well-rounded  and  containing  numerous  fluid  inclusions  ;  some  patches  of 
chlorite  ;  numerous  grains  of  epidote  ;  a  little  sahalite,  and  large  masses  of  zoisite. 

Ancient  Rocks  of  Sedimentary  Origin  on  Cape  Ann.  —  The  principal 
and  largest  mass  of  this  sedimentary  rock  is  seen  on  the  shore  at  the  west- 
erly side  of  Folly  point,  east  of  Langford's  cove,  at  Lanesville.  This 
outcrop  varies  in  width  from  ten  to  thirty  feet.  The  strike  is  north  40° 
east  to  southwest.  The  length  of  the  outcrop,  exposed  between  low 
water  and  the  covering  of  drift  on  the  hillside,  is  about  one  hundred  yards. 

The  microscopic  structure  is  :  well-rounded  grains  of  quartz  and  feldspar,  scales 
of  biotite,  some  titanite,  garnets  with  irregular  outline,  and  some  magnetite.  The 
larger  feldspars  have  inclusions  of  muscovite,  quartz,  and  epidote,  and  are  sur- 
rounded by  chlorite.  This  rock  is  clearly  a  mica-schist,  metamorphosed  from  a 
sandstone. 

Another  outcrop  of  this  mica-schist,  which  is  interbedded  with  a  gran- 
itic gneiss  and  chert,  is  seen  in  an  abandoned  quarry  in  the  Bay  View 
region.  It  has  the  same  dip  and  strike  as  the  outcrop  at  Lanesville. 
This  gneiss  has  the  same  microscopic  character  as  the  gneiss  of  Boxford 
and  Andover,  and  further  investigation  will  undoubtedly  show  that  this 
rock  belongs  to  the  lower  Cambrian  sediments,  thus  placing  in  this  group 
the  so-called  Archsean-gneiss  found  in  the  large  tract  in  the  northern 
part  of  the  County. 

On  both  sides  of  Brace's  cove,  Eastern  point,  Gloucester,  is  a  clearly 
metamorphosed  sedimentary  rock  of  irregular  outline  and  of  considerable 


Fig,   49.— MERRIMAC    RIVER    FLOWING    UNDER    THE    CHAIN    BRIDGE   AT    NEWBURYPORT. 
Quartz  diorite    rock  on    both  sides  of  the  river. 


Fig,    50.— CAMBRIAN    SLATY    SANDSTONE    LEDGE    AT    SOUTH    LAWRENCE. 
Used  (1901)  for  road   material. 


SLATE    OR    MICA-SCHIST  97 

extent,  with  a  strike  north  and  south  to  northeast  and  dip  nearly  vertical, 
and  which  is  also  seen  as  inclusions  in  the  hornblende  granite  of  the  region. 

The  microscopic  structure  is  :  rounded,  and  irregular  grains  of  quartz  and  feld- 
spars cemented  in  a  ground-mass  of  chlorite  and  limonite. 

Another  extensive  outcrop  is  seen  at  Essex,  in  the  valley  between 
White  and  Powder  House  hills,  and  extending  across  Essex  to  Conomo 
point.  Here,  the  slates,  which  are  distinctly  interbedded  with  gneiss 
and  quartzite,  are  in  places  filled  with  garnets  varying  from  microscopic 
size  to  one  fourth  of  an  inch  in  diameter.  These  slates  therefore  have 
been  metamorphosed  into  gametiferous-gneiss,  a  form  not  before  noticed 
in  Essex  County  rocks,  except  in  boulders  on  Cape  Ann  and  Nahant.  As 
the  two  regions  last  named  are  in  direct  line  with  the  variations  of  the 
glacial  striae  on  the  surface  of  the  rocks  throughout  the  County,  it  may 
be  presumed  that  these  isolated  boulders  are  remnants  of  glacial  material 
originating  in  this  outcrop  in  Essex. 

Opposite  Magnolia,  on  the  western  side  of  Kettle  cove,  is  a  bedded 
series  of  arkose  conglomerates,  indicating  that  some  earlier  form  of  granite 
has  been  reduced  to  gravel  and  reconsolidated. 

A  bed  of  ancient  sediments  also  outcrops  on  the  harbor  on  the  western 
side  of  Misery  island,  and  extends  nearly  to  the  northwestern  point,  a  dis- 
tance of  294  yards.  These  bedded  rocks  are  known  as  schiefferhorn- 
fels,  and  were  so  named  by  Professor  Rosenbusch  of  the  University  of 
Heidelberg.  The  rock  is  produced  from  the  decomposition  of  a  diabase 
tufa,  and  contains  augite  in  grains  and  stringy  pieces,  which  is  contrary 
to  the  theory  of  a  sedimentary  rock.  In  the  photomicrograph  (see  Fig. 
51)  the  augite  is  shown  in  the  black  color  in  ragged  lines. 

Slate  or  Mica-Schist.  —  These  rock-masses  are  usually  interstratified 
with  sandstone,  and  the  schist  is  undoubtedly  a  metamorphosed  slate. 
Nearly  all  of  the  bed-rock  of  West  Newbury,  Groveland,  Haverhill,  Law- 
rence, and  Methuen  is  composed  of  this  metamorphic  slate. 

The  outcrops  north  of  the  granite  area  in  South  Lawrence  and  West 
Andover,  and  extending  into  Salem,  N.  H.,  are 'a  metamorphosed  slate 
and  sandstone,  now  transformed  into  a  hard  mica-schist,  the  strike  of 
which  is  northeast  to  southwest,  varying  from  10°  north  of  east  to  north- 
east. Near  the  gneissic  granite  quarries  of  the  Essex  Company  in  South 
Lawrence,  these  slates  in  part  are  less  metamorphosed,  and  are  simply 
phillite  slates  much  crumpled  and  sheared  and  showing  considerable 
regional  distortion,  due  to  lateral  pressure  by  the  intrusion  of  an  olivin 


98  SLATE    OR    MICA-SCHIST 

basalt  or  dike  rock.  Near  the  contact  of  the  slate  and  one  of  these  dikes 
the  former  is  full  of  vesicles  —  a  typical  scoria.  At  a  contact  with  the 
dike  and  the  granitic  gneiss,  the  latter  is  calcined  and  baked  to  a  hard 
bluish-grey  rock.  Within  three  hundred  yards  of  the  granite  quarries 
before  mentioned,  and  in  a  northwesterly  direction,  the  mica-schists  and 
less  metamorphosed  slates  form  an  outcrop  by  the  roadside.  The  bedding 
of  the  slate  shows  very  distinctly  but  is  somewhat  crumpled,  owing  to 
the  veins  of  granite  which  cut  through  the  rock.  The  strike  is  northeast 
to  southwest  and  the  dip  is  nearly  vertical. 

The  microscopic  structure  of  the  metamorphic  slate,  in  the  bed  of  the  Merrimac 
river,  below  the  Lawrence  dam  is:  clastic  grains  of  quartz  sand  ;  some  secondary 
quartz  surrounded  with  earthy  yellowish  kaolin  and  chlorite  masses  ;  titaniferous 
magnetite  and  leucoxene  ;  and  a  few  grains  of  plagioclase  with  inclusions  of  apatite, 
zircons,  and  fibrolite.  The  quartz  grains  show  evidence  of  crushing,  embryonic 
cracks  are  developed,  and  some  of  the  grains  are  broken  and  the  pieces  faulted 
two,  and  in  one  instance  three  times. 

On  Canal  street.  South  Lawrence,  southwesterly  from  the  dam  across 
the  Merrimac  river,  there  is  an  outcrop  of  Cambrian  slate  and  another 
may  be  seen  near  the  comer  of  Crosby  street. 

Other  outcrops  of  slate  occur  on  both  sides  of  the  river  road  and  extend 
nearly  to  the  West  Andover  crossroad,  north  of  Fish  brook.  Toward  the 
west  the  outcrops  near  the  Dracut  town  line  are  more  slaty,  showing 
less  metamorphism.  One  outcrop  near  Bartlett's  brook  is  a  typical 
argillite  slate,  and  similar  outcrops  may  be  formd  at  the  south  and  east 
of  Harris'  pond  in  Methuen  and  elsewhere  in  the  town.  Near  the  state 
line,  and  on  both  sides  of  the  Spicket  river,  the  slate  is  interstratified  with 
sandstone.  North  of  the  village  of  Methuen  there  are  large  outcropping 
ledges  of  the  slates  which  have  been  used  for  road  building.  The  original 
format'on  has  been  greatly  changed  to  a  very  hard  blue  schist,  by  the 
intrusion  of  massive  dikes  of  granite  and  diabase.  Between  Bear  Meadow 
brook  and  Lone  Tree  hill,  on  the  west  side  of  Methuen,  there  is  an  outcrop 
of  slate  and  sandstone  with  a  strike  north  20°  east;  south  20°  west.  Frag- 
ments of  Hyolithes  fossils  and  casts  of  annelids  are  frequently  found  in 
these  slates.  Fragments  of  Hyolithes  are  also  abundant  in  the  city  ledge 
at  South  Lawrence  where  the  slate  is  interstratified  with  a  fine  sandstone 
containing  calcite.     (See  Fig.  50.) 

Nearly  all  of  the  bed-rock  of  Methuen  is  composed  of  this  metamorphic 
slate  and  a  coarse  mica-schist,  of  the  same  composition  as  that  from  Law- 


Fig.    51.  — PHOTOMICROGRAPH    OF    SCHIEFFERHORNFELS. 
West  cove,    Misery  island. 


m 


Jk 


Fig.    52-  — PHOTOMICROGRAPH-OF    QUARTZITE    SANDSTONE. 
South  Georgetown. 


SLATE    OR    MICA-SCHIST  101 

rence,  Haverhill,  and  Gage's  hill  in  Bradford.  In  Methuen,  this  slate  and 
schist  formation  is  over  one  thousand  feet  in  thickness,  and  its  trend  is 
north  40°  east-southwest;  dip  45°  west.  Nearly  every  outcrop  from  West 
Andover  across  Lawrence,  Methuen,  Bradford,  Haverhill,  Merrimac,  South 
Hampton,  Hampton  Falls,  and  North  Hampton,  to  Rye,  in  this  strike,  is 
composed  of  these  same  metamorphic  slates  and  schists. 

At  Andover,  the  Shawsheen  river  cuts  its  channel  through  Cambrian 
red  limestone  and  slate,  a  fact  which  was  clearly  shown  in  1899,  when  the 
foundation  was  laid  for  the  new  dam  of  the  Stevens  Woolen  Mills. 

In  Merrimac,  there  are  only  two  outcrops  of  bed-rock,  one,  south  of 
Cobbler's  brook  on  the  river  road,  and  the  other,  in  a  cutting  made  by 
the  electric  railway.  They  are  both  slaty  mica-schists,  a  metamorphosed 
form  of  slate  and  sandstone.  On  the  southern  side  of  the  Merrimac  river 
these  slaty  sandstones  also  make  their  appearance  and  form  the  bank 
of  the  river  extending  from  the  Artichoke  river  westerly  across  West  New- 
bury and  Groveland.  Large  outcrops  also  appear  near  Pipe  Stave  hill, 
Archelaus  hill,  and  west  of  Indian  hill. 

A  crumpled  metamorphic  slate  found  in  West  Newbury,  north  of  the 
First  Congregational  church,  is  greatly  decomposed  on  the  surface  of 
the  outcrop.  It  has  a  strike  north  10°  east,  to  south  10°  west.  The  dip 
is  nearly  vertical,  being  slightly  west. 

The  microscopical  structure  shows  quartz  grains  with  fluid  inclusions  of  car- 
bonic acid,  much  muscovite,  and  muscovite  interlaminated  and  cemented  with 
ferrous  oxides  and  limonite.  Many  of  the  quartz  grains  show  incipient  cracks, 
while  some  of  them  are  broken  and  crushed  or  faulted.  The  feldspars,  by  decom- 
position, have  produced  kaolins  and  earthy  chlorite. 

At  Bradford,  Little  Niagara  brook  cuts  its  course  through  slate  and 
sandstone  and  has  a  steep  waterfall,  suggesting  the  name  applied  to  the 
brook.  At  Mitchell's  falls,  north  of  Kimball's  island,  in  the  Merrimac 
river,  the  Cambrian  slates  metamorphosed  into  hard  mica-schists  with 
veins  of  calcite,  turn  the  course  of  the  river  towards  the  north  and  around 
Ward  hill,  a  massive  outcrop  of  this  mica-schist.  At  the  southeast  of  the 
hill  the  rock  outcrops  and  is  seen  for  three  hundred  yards  in  a  cutting 
made  for  the  railroad. 

The  microscopical  structure  of  this  metamorphic  slate  shows  angular  and 
rounded  grains  of  quartz  in  abundance,  with  a  few  grains  of  feldspar,  muscovite, 
biotite,  and  chlorite,  developed  in  the  plane  of  cleavage  of  the  rock-mass.  Titanite, 
with  its  decomposition  product,  leucoxene,  is  seen  in  parts  of  the  section.     Rutile 


102  SLATE    OR    MICA-SCHIST 

and  magnetite  occur  in  the  chlorite  areas.  The  larger  quartz  grains  are  filled  with 
fluid  inclusions  and  show  incipient  cracks  in  all  stages.  Some  sections  of  these 
slates  found  in  the  northern  part  of  Methuen  on  the  bank  of  the  Spicket  river,  are 
so  completely  metamorphosed  that  little  else  can  be  recognized  than  quartz  and 
an  earthy  kaolin  with  titaniferous  magnetite.  The  metamorphism  is  so  complete 
that  single  grains  of  quartz  are  often  seen  broken  and  faulted  two  or  three  times. 

South  of  the  Ward  Hill  railroad  station  the  road  bed  cuts  through  a 
massive  basalt  dike,  at  a  contact  of  the  metamorphic  slate  with  the  coarse 
mica  hornblende  granite  of  North  Andover.  From  Ayer's  Village,  Haver- 
hill, towards  the  north  and  northeast  and  extending  into  Atkinson,  N.H., 
are  numerous  outcrops  of  slate  and  sandstone,  cut  parallel  to  the  bedding 
of  the  slate  and  intersected  by  veins  of  granitic  gneiss  containing  veins 
of  pegmatite.  North  of  Crystal  lake,  Haverhill,  wherever  the  outcrop  of 
granitic  gneiss  becomes  massive  it  has  large  blocks  of  slate  taken  up  by 
the  gneiss  in  the  flow  of  the  magma,  previous  to  its  consolidation,  and 
thereby  showing  this  gneiss  to  be  an  intrusive  eruptive  rock. 

Veins  and  dike-like  masses  of  this  granite  cut  through  the  slate-beds 
or  mica-schists  of  Methuen  and  Lawrence.  An  outcrop  is  foiuid  southeast 
of  Ayer's  hill  in  Methuen,  and  another  occurs  west  of  Bear  Meadow  brook, 
where  both  slate  and  granitic  gneiss  appear.  Several  outcrops  formerly 
existing  in  Lawrence,  within  the  city  limits,  are  now  concealed  by  build- 
ings, among  others,  one  between  Appleton  and  Jackson  streets,  another 
at  Court  place,  and  a  third,  at  the  comer  of  Brook  street,  near  the  Spicket 
river. 

The  microscopical  structure  of  a  metamorphic  slate  from  the  Cannon  hill  area 
in  Groveland,  shows  many  detrited  grains  of  quartz,  angular  and  well-rounded;  a 
little  secondary  quartz  ;  rounded  grains  of  orthoclase  largely  kaolinized  ;  earthy 
biotite,  abundant  in  long  flat  crystal  forms  in  the  plane  of  the  schistosity  of  the 
slate  ;  a  few  plates  of  muscovite  ;  titaniferous  magnetite  with  leucoxene  ;  rutile  in 
needle-shaped  crystals  to  be  seen  in  some  chlorite  masses.  Some  of  the  quartz  grains 
are  crushed  and  broken  by  the  pressure  which  caused  the  metamorphism  of  these  beds. 

North  of  the  Merrimac  river,  opposite  the  town  of  Groveland,  the 
slaty  sandstones  cut  by  veins  of  granite  come  to  the  surface,  appearing 
on  the  west  side  of  Kenoza  lake,  at  Riverside,  and  southeast  of  Corliss 
hill.  At  Riverside,  on  Groveland  street,  there  is  an  outcrop  of  a  highly 
metamorphosed  slaty  rock,  cut  by  veins  of  granitic  gneiss.  In  1890,  a 
stone-crusher  was  installed  here  to  reduce  the  ledge  for  road-building 
material.     One  mass  of  the  rock  was  found  to  be  a  very  basic  eruptive. 


Fig.    53.  — CAMBRIAN    LIMESTONE    AND    CHERT. 
East   Point,    Nahant. 


Fig.    54.  — CAMBRIAN    LIMESTONE    AND    CHERT    CUT    BY   A    MASSIVE    BASALT    DIKE. 
North   of   Pulpit  rock,    East  point,    Nahant. 


SLATE    OR    MICA-SCHIST  105 

penetrating  and  metamorphosing  the  slate  to  a  sericite-schist  in  which 
the  sericite  penetrated  plates  of  biotite  crosswise  to  the  basal  cleavage. 
Probably  this  rock  was  originally  a  sericite  phyllite. 

The  microscopic  structure  of  a  metamorphic  slate  from  East  Haverhill,  as 
shown  b}^  five  sections,  is:  angtdar  and  rounded  grains  of  quartz  in  some  of  which 
are  nttmerous  fluid  inclusions  ;  several  quartz  grains  in  the  line  of  the  schisosity 
of  the  rock-mass,  showing  cracks  from  all  the  incipient  stages  to  the  broken  and 
crushed  masses  ;  feldspar  grains  much  kaolinized  and  showing  the  effect  of  crush- 
ing, some  of  the  grains  being  broken  into  several  pieces  ;  scales  of  muscovite  and 
biotite  arranged  in  layers  parallel  to  the  schistosity  of  the  rock-mass  ;  and  inclu- 
sions of  apatite,  zircons,  fibrolite,  and  rutile  abundant  in  the  kaolinized  feldspars. 
Titaniferous  magnetite  and  leucoxene  are  scattered  through  the  sections,  and  fine 
acute  rhombs  and  long  lath-shaped  sections  of  titanite  are  seen  in  one  of  the  thin 
sections. 

In  the  roadway  east  and  south  of  Archelaus  hill.  West  Newbury, 
outcrops  of  red  limestone  and  slate  occur  containing  fossil  Hyoliihes. 
These  beds  also  outcrop  on  Prospect  street,  Bridge  street,  Bailey's  lane, 
and  on  the  bank  of  the  Merrimac,  north  of  Long  hill.  At  the  base  of 
Brake  hill.  West  Newbury,  there  is  an  outcrop  on  both  sides  of  the  road, 
extending  for  over  i,ooo  yards.  Here  the  slate  and  sandstone  are  inter- 
stratified  and  the  slate  is  greatly  sheared  and  very  fissle.  On  Pleasant 
street,  an  old  quarry  shows  similar  forms,  many  blocks  of  the  slate  having 
a  crumpled  appearance.  These  Cambrian  sedimentary  rocks  here  occupy 
an  area  of  about  nine  square  miles. 

An  intrusive  granite  protogine  gneiss,  cutting  remnants  of  sedimentary 
beds  of  shale  and  sandstone  in  the  bed  of  the  Merrimac,  is  found  one  eighth 
of  a  mile  west  of  the  Chain  bridge  at  Newburyport.  This  gneiss  shows 
that  the  minerals  of  the  intrusive  rock  and  also  the  shaly  slate  have  been 
greatly  metamorphosed. 

The  microscopical  structure  shows  that  a  large  proportion  of  this  rock  is  com- 
posed of  rounded  grains  of  quartz,  some  grains  of  orthoclase  and  plagioclase,  mus- 
covite, and  garnet  with  magnetite  and  limonite.  The  feldspar  grains  are  filled  with 
inclusions  of  quartz  and  muscovite,  as  a  micrographic  structure.  Some  larger 
plates  of  muscovite  have  numerous  inclusions  of  zircons,  which  show  fine  pleochroic 
halos  as  the  stage  of  the  microscope  is  revolved  90°,  the  halos  appearing  and  dis- 
appearing. The  garnets  are  crushed  and  broken,  showing  that  they  have  been 
subjected  to  great  pressure  and  strain. 

The  shaly  slate  shows  numerous  quartz  grains  having  incipient  cracks  and 
broken  grains,  with  numerous  inclusions  of  zircons  and  garnets.  There  are  also 
larger  lenses  of  secondary  silica  in  the  line  of  cleavage.     Some  grains  of  orthoclase 


106  SLATE    OR    MICA-SCHIST 

appear  badly  decomposed.  Earthy  kaolin,  chlorite,  epidote,  titanite,  and  some 
leucoxene  appear,  and  muscovite,  biotite,  and  titanite  grains  are  arranged  in  the 
plane  of  cleavage  of  the  slate. 

On  Kent's  island  in  Newbury,  at  the  junction  of  Little  and  Parker 
rivers,  there  is  a  bed  of  argillite  interstratified  with  sandstone,  which 
extends  about  one  thousand  yards  on  the  bank  of  the  Parker  river  to  a 
point  near  the  railroad,  and  on  Little  river  one  h^^ndred  yards  west.  Some 
of  the  beds  are  of  a  dull  red  color,  resembling  the  North  Attleboro  and 
North  Weymouth  slates,  while  others  are  of  a  greenish  color.  They  are 
cut  in  several  directions  and  are  distorted  by  felsites  and  amygdaloidal 
melaphyres,  shearing  and  faulting  to  such  an  extent  that  the  true  bedding 
is  quite  difficult  to  determine.  By  uncovering  the  glaciated  surface, 
however,  and  washing  away  the  clay  and  drift,  the  bedding  is  plainly 
revealed.     The  strike  is  50°  north  of  east;  dip  55°  southwest. 

The  microscopic  structure  of  a  very  opaque  section  of  the  red  slate,  cut  across 
the  bedding  is:  clastic  quartz  grains  and  fragments,  showing  secondary  enlargement 
and  crushing  and  containing  ntmierous  fluid  inclusions,  surrounded  by  a  ground- 
mass  of  earthy  kaolin;  much  muscovite  and  ferruginous  magnetite  and  limonite. 
The  sections  of  the  green  slate  from  Little  river  are  composed  of  angular  and  rounded 
quartz  grains  ;  a  finely  fibrous  kaolinized  ground-mass  ;  some  epidote,  muscovite,  a 
few  grains  of  zoisite,  and  much  chlorite.  The  alternating  sandstone  is  composed  of 
quartz  and  feldspar  grains,  some  biotite  and  scales  of  muscovite,  and  much  ferritic 
oxide. 

Several  outcrops  of  Middle-Cambrian  sedimentary  rocks,  blue  limestones, 
blue  and  red  slates,  and  quartzite,  appear  south  of  the  Ipswich  river  in 
Topsfield.  Fossil  HyoUthes,  Stenotheca,  a  fossil  resembling  a  minute  sponge, 
a  fossil  coral,  and  numerous  casts  of  annelids  have  been  found  in  thin 
sections  of  the  blue  limestone.  These  Cambrian  rocks  are  cut  by  horn- 
blende diorite  and  are  intimately  associated  with  an  ancient  arkose  con- 
glomerate granite  which  occurs  in  the  immediate  region  of  the  slate.  In 
fact  the  slate  seems  to  have  surrounded  the  arkose,  but  an  exact  contact 
does  not  occur.  On  the  Pike  farm,  a  large  outcrop  of  chert  or  metamor- 
phosed limestone  appears.  On  Cross  street,  near  the  "Donation  Farm," 
the  arkose  granite  occurs  in  the  form  of  a  massive  ferruginous  arkose  of 
Pre-Cambrian  age.  Other  outcrops  appear  on  the  summit  of  Price's  hill 
and  in  the  "sugar  loaf"  hills  about  the  village.  Five  of  these  "sugar 
loaf"  hills  have  been  opened,  and  all  are  arkose  covered  with  a  thin  coat- 
ing of  drift,  sand,  and  gravel.     It  is  a  typical  conglomerate  granite,  con- 


Fig.    55.  — HORNBLENDE    DIORITE    LEDGE    ON    THE    PICKMAN    ESTATE. 
South   Salem. 


-HORNBLENDE    DIORITE    LEDGE    IN    PROCESS    OF   REMOVAL    BY    THE    MASSACHUSETTS 
BROKEN    STONE    COMPANY,     1898.     CASTLE    HILL,    SALEM. 


SLATE    OR    MICA-SCHIST  109 

taining  pebbles  of  a  ferruginous  limestone  and  coarse  mica-schist,  sur. 
rounded  by  pebbles  and  masses  of  the  arkose.  The  presence  of  such  a 
large  body  of  this  arkose  indicates  that  the  area  was  formerly  an  ancient 
land  created  long  before  the  formation  of  the  Lower  Cambrian  sediments. 

South  of  the  village  of  Topsfield,  by  the  side  of  High  street,  there  are 
outcrops  of  Cambrian  slates,  and  a  small  hill  on  the  western  side  of  Perkins 
street  is  largely  composed  of  Cambrian  limestone.  On  the  Clark  farm, 
about  two  miles  from  this  hill,  are  several  outcrops  of  Cambrian  quartzite, 
slates,  and  cherty  limestones,  and  continuing  in  this  northeasterly  direction, 
other  outcrops  may  be  seen  by  the  roadside  near  the  base  of  Little  Turner's 
hill  in  Ipswich. 

At  West  Boxford,  the  hill  between  the  forks  of  the  roads  leading  to 
Bradford  and  Groveland,  is  largely  a  sedimentary  slate  and  cherty  lime- 
stone, and  this  outcrop  is  also  nearly  continuous  on  both  sides  of  the  Up- 
tack  hill  road  in  Groveland  and  Georgetown.  South  of  the  Lakeside 
farm,  a  western  extension  of  Uptack  hill  having  an  elevation  of  220  feet 
above  mean  sea-level  is  almost  entirely  composed  of  a  cherty  limestone 
and  slate. 

The  microscopical  structure  of  the  metamorphic  slate  from  the  area  extending 
from  Johnson's  pond,  West  Boxford,  to  the  north  of  Chadwick's  pond,  shows  numer- 
ous sub-angular  and  rounded  grains  of  quartz  ;  rounded  and  broken  grains  of  ortho- 
clase  and  albite  ;  plates  of  biotite  and  muscovite  ;  some  cordierite,  chlorite,  earthy 
kaolin,  and  limonite.     The  cement  is  formed  by  the  earthy  kaolin  and  limonite. 

On  both  sides  of  Little  pond.  West  Boxford,  are  outcrops  of  sedimen- 
tary beds  which  resemble  hornblende  epidote  gneiss,  but  upon  close  ex- 
amination are  seen  to  be  Cambrian  sedimentary  rocks.  Towards  the 
southeast  from  Little  pond,  where  prospectors  have  blasted  for  silver, 
the  rock  is  a  blue  limestone  and  chert.  A  mile  to  the  north,  where 
the  road  crosses  a  brook,  an  inlet  to  Johnson's  pond,  outcrops  of  slate 
and  sandstone  occur  in  the  bed  of  the  brook.  On  the  bank  of  the  mill 
pond  in  Groveland,  near  the  electric  railway,  is  another  outcrop  of  these 
sedimentary  rocks.  The  road  from  West  Boxford  to  South  Groveland 
winds  upward  through  the  Cambrian  sedimentary  rocks,  and  at  the  high- 
est point  there  is  a  wide  vein  of  fine  micaceous  granite,  a  very  handsome 
rock.  These  vein-granites  also  outcrop  on  the  top  of  the  hill  at  the  Wash- 
ington street  cutting,  and  on  the  same  street  there  is  a  massive  dike  of 
hypersthene  diallage  gabbro,  in  places  fifteen  feet  wide,  which  cuts  all 


110  SLATE    OR    MICA-SCHIST 

the  other  members  of  this  series  of  granites,  together  with  the  sedimentary- 
beds  and  the  hornblende  epidote  gneiss  as  well. 

Red  Shank  hill,  in  South  GeorgetoAvn,  is  a  large  outcrop  of  ferruginous 
slate  and  schist  of  sedimentary  origin.  This  rock  also  appears  in  the 
cellar  of  the  Town  Hall  at  Georgetown.  Nubbly  hill  and  Nelson's  hill 
are  both  outcrops  of  a  quartzite  having  a  strike  northwest  to  southeast 
or  directly  opposite  from  the  strike  of  other  outcrops  in  this  area,  with 
one  exception  —  Red  Shank  hill,  on  which  a  massive  dike  has  cut  half- 
way to  the  top  and  forced  a  portion  of  the  sedimentary  beds  from  the 
southeast  around  to  the  northwest. 

Between  Nelson  street,  South  Georgetown,  and  Perley's  pond,  Boxford, 
there  is  an  outcrop  of  slate-sandstone  and  quartzite  (see  Fig.  52)  in  which 
a  cutting,  twenty  feet  deep,  was  made  a  few  years  ago  while  prospecting 
for  gold.  At  a  contact  of  the  sandstone  and  gneissic  hornblende  diorite, 
a  vein  of  grey  copper  was  exposed. 

North  of  the  old  "  lime-pits,"  near  Steven's  pond  in  Boxford,  there  are 
outcrops  of  slate,  sandstone,  and  quartzite. 

The  microscopical  structure  of  a  ferruginous  metamorphic  slate  from  Chaplin- 
ville,  Rowley,  taken  from  between  Hunslow  hill  and  Prospect  hiU,  is  as  follows  : 
angular  and  rounded  grains  of  quartz  ;  feldspar  grains  with  some  smaU  plates  of 
muscovite  and  biotite ;  small  crystalline  plates  of  calcite,  cemented  together  with  an 
iron  oxide,  probably  limonite.  Most  of  the  muscovite  plates  are  arranged  in  lines 
parallel  to  the  bedding.  The  quartz  and  feldspar  grains  show  perfect  outlines  and 
do  not  exhibit  the  broken  and  crushed  appearance  seen  in  more  metamorphic 
slates,  especially  near  the  granite  and  quartz  diorite  areas. 

The  Cambrian  outcrops  of  quartzite  and  slate  at  Ljmnfield  Centre 
were  studied  in  1898,  when  a  well  was  opened  in  the  cellar  of  a  house 
owned  by  H.  B.  Nesbit.  The  dip  was  35°  west  and  the  strike  north  and 
south.  At  the  bottom  of  the  well,  twenty-eight  feet  below  the  surface, 
the  slate  contained  much  graphite.  Above  the  slate-beds  was  found 
white  limestone  interstratified  with  a  light  blue  slate  and  quartzite.  Al- 
though no  fossils  were  discovered,  the  lithological  character  of  the  rock 
and  the  form  of  the  beds  indicated  an  Olenellus  Lower  Cambrian  sedi- 
mentary rock. 

The  microscopic  structure  of  a  quartzite  from  Lynnfield  Centre  is:  quartz  grains 
containing  numerous  fluid  inclusions  and  incipient  cracks;  also  crushed  and  broken 
grains  produced  by  pressure  in  the  rock-mass  during  metamorphism ;  much  secon- 
dary quartz,  which,  with  the  polariscope,  gives  the  usual  wavy  extinctions  ;  some 


Fig.    57.  — HORNBLENDE    DIORITE    OUTCROP. 
In  the   "Nubble    Squid,"    Groveland, 


BKB^mHBBKefetf''^^J£?*j;  ^Ss 

'  =';:  ■J'-'v:;  '^^^«-'-/ip.4^«t» 

.Vr   ^-~0      iiSs*r,  .■^-•/ r-'-x^ ' 

l^sB 

Fig.    58.  — SPLIT    BOULDER    OF    HORNBLENDE    DIORITE. 
Near  the   "  Nubble   Squid,"    Groveland. 


SLATE    OR    MICA-SCHIST  113 

grains  of  secondary  glassy  plagioclase ;  perfectly  fresh  grains  of  microcline ;  orthoclase 
kaolinized  and  much  decomposed,  with  numerous  inclusions  of  zircons  and  apatite 
crystals ;  some  chlorite,  and  a  little  biotite.  An  outcrop  at  this  point  is  exposed  for 
a  distance  of  one  hundred  yards  and  is  in  some  places  finely  schistose  and  laminated, 
while  in  others  it  is  massive.     The  strike  is  north  20°  east  ;  dip  50°  west. 

On  the  eastern  side  of  Breakheart  hill,  in  Saugus,  between  the  base 
of  the  hill  and  Saugus  river,  are  several  outcrops  of  Cambrian  slates  and 
metamorphosed  limestones  in  contact  with  aporhyolites.  At  this  contact 
the  slates  have  become  metamorphosed  into  a  knotted-schist,  or  knottin- 
schieffer,  and  in  some  places  a  typical  fiickinschieffer  has  resulted  in  all 
gradations,  from  the  typical  slate  to  the  knotted  and  variously  blotched 
forms  of  these  schists.  Higher  up  the  hill  the  quartzite  becomes  a  quartzite- 
conglomerate  in  various  forms,  from  fine  gravel-like  pebbles  to  a  coarse 
gravel  in  which  all  of  the  pebbles  are  quartzite,  with  a  quartz  cement 
holding  them  together  and  forming  a  very  hard  tough  rock.  A  boulder 
of  this  quartzite-conglomerate,  weighing  several  tons,  maybe  seen  (1904)  on 
the  Lynn  harbor  side  of  Little  Nahant.  Without  doubt  this  boulder  was 
detached  from  the  ledge  on  Breakheart  hill  and  rafted  across  Lynn  harbor 
during 'the  Glacial  period. 

At  North  Saugus,  near  the  comer  of  Main  and  Oak  streets,  there  is 
an  outcrop  of  metamorphic  slate  interstratified  with  a  quartzite,  and  on 
Main  street,  two  hundred  yards  east  of  the  school-house,  the  homblendic 
eruptive  granite  cuts  directly  across  this  metamorphic  slate  and  includes 
large  fragments.  The  strike  of  these  metamorphic  slates  and  quartzites 
is  north  20°  east,  and  parallel  to  that  of  similar  beds  at  Lynnfield  Centre. 

The  microscopic  structure  of  this  metamorphic  slate  is  :  clastic  quartz  grains 
with  many  fluid  inclusions  ;  well-rounded  grains  of  plagioclase  ;  orthoclase  almost 
entirely  decomposed  ;  biotite  ;  some  muscovite,  and  magnetite  ;  ground-mass,  a 
ferruginous  earthy  kaolin  with  some  fibrous  chlorite,  and  a  few  grains  of  epidote. 
The  quartzite  from  the  same  place  in  thin  section  shows  :  quartz  grains  with 
numerous  fluid  inclusions  ;  feldspars  much  kaolinized  and  containing  numerous 
inclusions  of  apatite,  tourmaline,  and  epidote  ;  while  patches  of  chlorite  are  often 
seen  in  the  line  of  the  bedding.  The  whole  rock-mass  is  thoroughh'  saturated 
with  a  ferruginous  limonite,  giving  it  a  dirty  yellowish  color. 

An  outcrop  of  Cambrian  slate  at  Crescent  beach,  Nahant,  shows 
considerable  metamorphism,  and  is  the  same  as  the  slate  found  at  Wyoma 
in  Lynn.  At  the  beach,  the  cleavage,  which  has  been  developed  cross- 
wise to  the  original  bedding  planes,  is  much  wider  than  the  secondary 


114  SLATE    OR    MICA-SCHIST 

cleavage  planes  in  the  rock  at  Wyoma  and  is  filled  with  andalusite,  showing 
the  fine  pink  color  of  that  mineral. 

The  microscopical  structure  of  this  metamorphic  slate  shows  quartz  grains  of 
a  detrital  character  with  evidences  of  crushing.  Incipient  cracks  across  the  grains 
are  common  in  all  sections  of  the  rock.  Orthoclase,  deeply  kaolinized  in  well-rounded 
grains  appears;  a  few  grains  of  albite;  biotite,  usually  in  layers  in  the  line  of  the 
bedding  of  the  slate,  and  numerous  fine  grains  of  magnetite  appearing  thickly 
through  the  minerals  in  all  parts  of  the  section.  A  secondary  cleavage  crosswise 
to  the  bedding  has  been  developed  and  is  filled  with  a  slightly  pleochroic  reddish- 
pink  to  white  andalusite.  Grains  of  epidote  and  epidote  crystals  are  seen  in  the 
feldspar  grains.  Fluid  inclusions,  in  which  the  bubble  movement  is  quite  active, 
appear  in  some  of  the  quartz  grains. 

A  short  distance  north  of  Bennett's  head,  Nahant,  there  is  exposed 
at  low  tide  a  metamorphic  slate  having  a  strike  northeast  to  southwest. 
It  is  again  seen  at  Bass  point  in  the  southwest  part  of  the  town. 

The  microscopic  structure  of  this  slate  in  thin  section  is  :  grains  of  quartz  ;  some 
feldspar  in  bands,  alternating  with  dark  bands  composed  of  grains  of  quartz ;  grains 
of  magnetite  in  large  amount ;  flakes  of  biotite ;  some  flakes  of  chlorite  ;  muscovite ; 
and  a  large  number  of  grains  of  a  slightly  greenish  tinge,  giving,  with  the  polari- 
scope,  quite  high  single  refraction  and  often  showing  a  rectangular  prismatic  outline; 
parallel  extinction  commonly  giving  an  aggregate  fibrous  polarization.  These 
grains  may  be  andalusite  decomposed  to  muscovite  aggregates. 

On  the  southeast  side  of  Nahant  head,  dipping  under  the  banded  lime- 
stones, is  a  typical  argellite  slate. 

A  microscopic  examination  shows  an  abundance  of  muscovite  ;  numerous  quartz 
grains  with  fluid  and  microlithic  inclusions,  some  of  the  quartz  grains  showing  the 
incipient  cracks  and  partings  due  to  crushing  ;  well-rounded  grains  of  plagioclase, 
probably  derived  from  some  gneissic  formation,  with  quartz  and  numerous  micro- 
lithic inclusions.  The  ground-mass  is  composed  of  earthy  kaolin  and  fibrous  chlorite 
and  embedded  in  it  are  numerous  cubical  iron  pyrite  crystals. 

This  slate  is  again  seen  on  the  north  side  of  Little  Nahant,  where  it  is 
interstratified  with  a  coarse  mica-schist  containing  much  quartz,  some  of 
which  is  of  clastic  origin  and  still  shows  the  grains  of  original  quartz  sand. 

On  both  sides  of  Little  Nahant,  the  outcrops  of  slate  and  sandstone 
contain  numerous  fossil  HyoUihes.  Pea  island,  south  of  East  point,  is  a 
massive  outcrop  of  quartz  hornblende  gabbro.  The  Shag  rocks  are  cherty 
limestone  and  slate.  (See  Fig.  54.)  From  East  point  to  Bennett's  head, 
the   Olenellus   Cambrian   slate-chert  and  limestone   is   cut  by  numerous 


Fig.    59.  — DEVIL'S    DEN,    NEWBURY,     SHOWING    LIMESTONE    AND    SERPENTINE    IN    THE    FOREGROUND. 


Fig   ■  60.  — DEVIL'S    DEN,    NEWBURY,    SHOWING    A    QUARTZ    HORNBLENDE    DIORITE    FORMATION, 


SANDSTONE  117 

basic' dikes,  one  of  which  is  an  ohvin  basalt.  (See  Fig.  53.)  This  Hme- 
stone  contains  numerous  fossil  Hyolithes,  Stenoiheca,  brachiopods,  etc.  The 
nearest  bed  of  metamorphic  sedimentary  rock  is  the  outcrop  near  Flying 
point,  Marblehead  Neck.  This  rock-mass  is  now  a  mica-schist  metamor- 
phosed from  slate,  and  is  cut  and  greatly  distorted  by  the  eruptive  granite. 

The  microscopic  structure  of  this  rock-mass  as  shown  by  several  thin  sections 
is  as  follows :  several  grains  of  microcHne  well  twinned  with  numerous  inclusions 
of  micro-zircons  ;  orthoclase  much  kaolinized  and  earthy  ;  quartz  in  angular  and 
rounded  grains,  some  crushed  and  broken  and  many  showing  incipient  cracks  due, 
no  doubt,  to  local  metamorphism  ;  much  muscovite  and  biotite  lying  in  the  plane  of 
the  schistosity  ;  a  few  grains  of  epidote  ;  fragments  of  white  garnets,  and  numerous 
large  patches  of  red  garnets  which  are  much  broken  and  crushed,  and  an  abund- 
ance of  magnetite  and  some  limonite. 

The  disintegration  of  this  rock  produces  the  magnetite  and  garnet 
sand  of  the  region.  Thin  sections  of  the  rock  in  a  road-cutting  at  the 
north  of  the  Atlantic  House  on  Marblehead  Neck,  exhibit  a  typical  quart- 
zite.  The  mica-schist  of  Naugus  head,  Marblehead,  and  Woodbury's 
point,  Beverly,  probably  belong  to  this  metamorphic  slate  although  the 
metamorphism  is  more  complete;  for,  in  these  last-named  outcrops,  the 
schist  is  not  only  cut  by  the  granite  but  it  is  also  cut  by  the  diorite,  eleeo- 
lite  zircon  syenite,  felsite,  and  diabase  dikes,  thus  making  the  metamor- 
phism of  the  rock-mass  most  intricate;  indeed,  as  pointed  out  by  Dr.  M. 
E.  Wadsworth,  the  eleeolite  zircon  syenite  has  been  injected  in  large  sheets 
into  these  schists,  in  the  planes  of  the  schistosity  and  jointings  of  this 
rock,  to  such  an  extent  that  in  some  places  it  is  puzzling  to  decide  which 
is  syenite  and  which  is  metamorphosed  slate. 

Microscopical  examination  shows  this  slate  to  be  composed  of  a  few  grains  of 
clastic  quartz  sand  ;  much  secondary  quartz  ;  secondary  glassy  feldspars;  some  mus- 
covite ;  an  abundance  of  biotite  which  is  probably  secondary ;  a  few  grains  of  epi- 
dote ;  apatite,  as  inclusions  in  the  ground-mass  which  is  feebly  polarizing  earthy 
kaolin  ;  much  magnetite,  red  garnets,  and  micro-zircons. 

Sandstone.  —  In  Andover,  near  Butterfield's  sawmiU,  is  an  outcrop  of 
metamorphic  micaceous  sandstone  lying  parallel  to  the  hornblende  schist 
on  the  east.  This  formation  is  again  found  at  the  John  Jenkins  farm  near 
the  crossroad  to  Ballardvale. 

The  microscopic  structure  of  sections  from  these  outcrops  is :  quartz  grains  of 
original  sand  cemented  by  a  film  of  ferreous  oxide  and  some   secondary  quartz, 


118  SANDSTONE 

scales  of  muscovite  and  biotite,  and  masses  of  fibrolite.  One  of  the  sections  from 
the  last-named  outcrop  is  composed  of  quartz  grains  and  angular  fragments,  with 
numerous  fluid  inclusions  showing  incipient  cracks  and  broken  grains,  much  mus- 
covite, some  biotite,  magnetite,  chlorite,  and  epidote. 

Another  large  area  of  the  metamorphic  slate,  interstratified  -with 
sandstone,  first  seen  near  a  small  pond  in  South  Groveland,  is  nearly- 
continuous  from  Johnson's  pond  in  West  Boxford  to  the  north  side  of 
Chad-wick's  pond  in  Bradford,  and  forms  all  the  adjoining  outcrops  for 
nearly  t-wo  miles  in  North  Andover. 

The  microscopic  structure  sho-wn  by  several  sections  is  :  well-rounded  original 
grains  of  quartz  and  plagioclase;  biotite;  muscovite;  a  little  chlorite  cemented  by 
a  thin  film  of  secondary  quartz  and  ferreous  oxide.  One  of  the  sections  contains 
magnetite  and  liraonite.  The  sandstone  is  composed  of  nearly  pure  quartz  sand, 
cemented  by  some  secondary  quartz  and  a  fibrous  feebly  polarizing  feldspathic 
mass  ;  fluid  inclusions  in  which  the  bubble  movement  is  quite  active  are  frequent 
in  the  quartz  grains. 

In  Middleton,  half  a  mile  southeast  of  the  village,  near  the  house  of 
Mr.  J.  U.  Parker,  is  a  -well-preserved  clastic  shale  approaching  a  sand- 
stone. This  outcrop  sho-ws  a  strike  nearly  northeast  to  south-west  -with 
the  dip  50°  north  of  -west.  It  is  again  seen  in  an  outcrop  in  the  rear  or  -west 
side  of  the  barn  of  Mr.  Francis  Peabody,  near  the  Ips-wich  river  on  the 
north  side  of  the  village. 

The  microscopic  structure  of  this  shale  is:  angular  and  rounded  grains  of  quartz 
which  show  embryonic  cracks  and  much  crushing,  and  in  some  grains  a  secondary 
enlargement;  plagioclase  twinned  feldspars,  broken  and  crushed,  some  of  which  are 
in  well-rounded  grains ;  ground-mass,  an  earthy  kaolin  with  plates  of  biotite ;  some 
muscovite;  and  an  abundance  of  magnetite  in  the  planes  of  the  schistosity  of  the 
shale.  Fine  inclusions  of  micro -zircons  are  seen  in  the  kaolinized  feldspars.  Some 
of  the  dark  opaque  patches  resemble  lignite,  and  it  is  not  impossible  that  this  shale 
is  carboniferous,  although  it  requires  more  field  work  and  lithological  study  to 
prove  it. 

In  the  line  of  the  strike  to  the  northeast,  across  the  Ips-wich  river  in 
Topsfield  and  on  the  land  of  Mr.  Peterson,  t-wo  hundred  yards  north-west 
of  the  old  Endicott  copper  mine,  this  shale,  -which  is  here  a  dull  red  color, 
protrudes  in  several  places.  It  is  interstratified  -with  a  ferruginous  sand- 
stone, the  strike  remaining  constant  —  northeast  to  south-west  -with  the 
dip  50°  -west. 


Fig.   61.  — STICKNEY    BOULDER,    GROVELAND. 
A   hornblende  diorite  rock  resting  upon   an  outcropping  ledge   of   hornblende  diorite. 


Fig.    62.  — SPLIT    BOULDER    OF    HORNBLENDE    DIORITE,    NEAR    THE    STICKNEY    BOULDER,    GROVELAND. 


LIMESTONE  121 

The  microscopic  structure  of  thin  sections  from  the  outcrop  near  the  roadside 
is  as  follows :  section  cut  across  the  bedding  —  ground-mass  of  earthy  kaolin  much 
discolored  with  a  ferruginous  iron  oxide;  magnetic  titanic  iron;  some  leucoxene; 
original  quartz  grains  showing  secondary  enlargements,  incipient  cracks  and  broken 
grains  and  also  fluid  inclusions ;  some  feldspars  much  decomposed  ;  muscovite  scales  ; 
green  chlorite ;  apatite ;  numerous  microliths  and  zircons ;  a  few  grains  of  zoisite  and 
epidote.  A  strongly  developed  shearing  to  the  north  accounts  for  the  crushed  and 
broken  appearance  of  the  quartz  and  feldspar  grains.  A  section  across  the  bedding 
from  a  specimen  of  the  outcrop  in  the  field  on  the  opposite  side  of  the  road,  near 
the  dwelling-house  of  Mr.  Peterson  shows:  ground-mass  composed  of  earthy  kaolin 
and  fibrous  chlorite ;  magnetite ;  titanif erous  iron  surrounded  by  leucoxene  ;  micro- 
zircons  ;  apatite ;  numerous  microliths  so  small  that  they  cannot  be  determined  with 
the  highest  power  of  the  microscope;  quartz  grains  with  numerous  fluid  inclusions; 
muscovite;  and  a  few  grains  of  zoisite  arranged  parallel  to  the  bedding.  Another 
section  of  ferruginous  sandstone  from  Peterson's  land  in  Topsfield  shows:  ground- 
mass  of  quartz  and  feldspar  grains;  numerous  flakes  of  muscovite  with  detrital 
angular  fragments  and  pebbles  of  the  quartz ;  feldspars  colored  with  f erreous  oxide ; 
some  epidote  and  chlorite  and  threads  of  calcite. 

Continuing  on  the  strike  of  this  shale,  there  are  two  outcrops  in  the 
northeastern  part  of  Topsfield,  one  in  Linebrook,  a  parish  of  Ipswich  on  Bull 
brook,  one  in  Rowley  near  John  Dodge's  mill,  and  another  near  tide-water 
between  Ipswich  village  and  Rowley.  The  microscopic  structure  of  the 
sections,  from  specimens  in  the  cabinet  of  the  Peabody  Academy  of  Science 
taken  from  these  localities,  is  nearly  the  same  as  that  of  the  last  two  from 
Topsfield.  Other  outcrops  of  these  clastic  shales  are  frequent  in  the 
northern  part  of  the  County.  On  the  southern  bank  of  the  Merrimac 
near  the  Artichoke  river,  there  is  a  large  area  of  this  shale  much  crumpled 
and  distorted  with  the  strike  north  and  south  and  dip  vertical.  Near  the 
point  where  Indian  river  empties  into  the  Merrimac,  the  shales  are  con- 
tinuous for  three  hundred  yards,  and  from  Bradford  across  North  Andover 
and  South  Lawrence,  in  a  southwest  course,  they  can  be  traced  in  an  al- 
most unbroken  line  to  West  Andover.  On  this  strike  the  shales  are  bedded 
between  the  granite  gneisses  on  the  south  and  the  metamorphic  slates  on 
the  north. 

Limestone.  —  x'lmong  the  most  interesting  of  the  stratified  rocks  are 
the  Nahant  limestones.  They  are  first  seen  on  the  south  side  of  Nahant 
head,  at  the  Shag  rocks,  and  extend  about  three  hundred  yards  to  a  point 
just  beyond  Bennett's  head  on  the  north.  These  limestones  are  much 
metamorphosed  into  bands  of  light  and  dark  lydite,  microscopic  sections 
of  which  reveal  calcite,  quartz  grains,  magnetite,  and  mica,  with  occasional 
masses  of  nearly  pure  calcite   interstratified   with  an  indurated  silicious 


122  .  LIMESTONE 

slate.  In  thin  sections,  under  the  microscope,  they  are  shown  to  be 
composed  of  calcite,  epidote,  quartz,  serpentine,  white  garnets,  and  limo- 
nite;  chlorite  tinges  portions  of  the  rock  green,  while  heraatite  and  limo- 
nite  turn  other  parts  red,  thus  giving  the  mass  a  brightly  banded  appear- 
ance, its  most  striking  feature  to  casual  observers.  By  means  of  certain 
fossils  which  have  been  found  in  this  rock  the  horizon  of  its  formation  is 
determined  as  the  Olenellus  Lower  Cambrian.  Mr.  Auguste  F.  Foerste 
first  described  one  of  these  fossils,  Hyolithes  incequilateralis ,  sp.  nov.,  in 
the  Proceedings  of  the  Boston  Society  of  Natural  History,  Vol.  24,  p. 
262,  and  numerous  specimens  have  since  been  collected  from  the  region, 
together  with  Hyolithes  princeps,  Hyolithes  communis,  var.  Emmonsi,  Hyo- 
lithes impar  and  Stenotheca  rugosa.  The  strike  of  this  limestone  is  18° 
north  of  east,  the  dip  4o°-43°  west. 

In  July,  1890,  an  outcrop  of  this  Olenellus  limestone  was  discovered 
in  a  valley  between  Prospect  hill  and  Hunslow  hill  in  Rowley.  It  has 
nearly  all  become  altered  to  chert  and  epidote,  but  fragments  of  the  Hyo- 
lithes are  still  to  be  found.  This  outcrop  dips  tinder  a  red  sandstone, 
which  in  turn  is  covered  with  the  fine-grained  granitic  gneiss  of  the  region. 
The  strike  of  this  outcrop  corresponds  very  nearly  with  that  of  the  Nahant 
rock  of  a  similar  character,  and  is  20°  north  of  east  with  a  dip  45°  west. 
A  mass  of  diorite,  known  as  Metcalf 's  rock,  cuts  across  this  limestone  on 
the  southeast  near  the  Ipswich  line,  and  on  the  north  it  is  covered  by  the 
banded  red  felsites  of  Byfield. 

Near  Bennett's  head,  Nahant,  the  strike  of  this  limestone  is  20°  west 
of  north,  dip  45°  southeast.  Here  the  limestone  rock-mass  has  been 
turned  or  pushed  one  side  by  the  intrusion  of  a  massive  dike  of  very 
unusual  character,  and  which  under  the  microscope  in  thin  section  is  seen 
to  be  composed  of  hypersthene,  olivin  somewhat  serpentinized,  diallage, 
plagioclase,  biotite,  numerous  brown  zircons,  magnetite,  a  little  calcite, 
and  brown  hornblende. 

In  limestone  the  most  common  metasomatic  change  is  dolomitization, 
the  process  by  which  calcite  is  converted  into  dolomite  by  the  replace- 
ment of  half  of  its  lime  by  magnesia.  Good  examples  of  more  or  less 
perfectly  dolomitized  rocks  occur  in  Newbury  near  the  Devil's  basin  and 
in  various  other  parts  of  the  town. 


Fig.   63.  — NORSEMAN'S    ROCK. 
A   quartz  hornblende  diorite   outcrop  in   West   Newbury. 


Fig.    64.  — CRADLE    ROCK,    GROVELAND. 
A  glacial    perched    boulder  of   diorite,   resting    upon   an   outcropping    edge   of  diorite. 


CHAPTER   IV 

THE    ERUPTIVE    PLUTONIC    ROCKS 

Quartz  Augite  Diorite.  —  This  formation  has  several  distinct  forms : 
quartz  augite  diorite,  quartz  hornblende  diorite  and  a  foliated  form  of 
the  same  type,  quartz  augite  mica  diorite  with  hornblende  diorite,  por- 
phyritic  diorite,  and  amphibolite.  It  has  its  greatest  development  in 
Newbury,  Newburyport,  and  Salisbury,  where  it  occupies  an  area  of  about 
12,800  acres.  In  a  southwesterly  direction,  extending  through  the  towns 
of  Georgetown,  Boxford,  Middleton,  and  Andover,  the  quartz  hornblende 
diorite  is  the  prevailing  rock.  The  form,  quartz  augite  diorite,  which  has 
been  taken  as  the  type,  may  be  seen  in  all  parts  of  both  areas. 

The  numerous  bed-rock  outcrops  by  the  roadside  in  the  towns  of 
Salisbury  and  Seabrook  are  quartz  augite  diorite,  sometimes  containing 
hornblende.  Outcrops  also  occur  at  Pettingill's  zinc  mine,  and  several 
small  outcrops  extend  to  a  point  north  of  the  Rocky  Hill  meeting-house. 
Eagle,  Carr,  Deer,  and  Ram  islands  in  the  Merrimac  river  are  nearly 
bare  ledges  of  this  rock,  which  also  occurs  north  of  John  True's  house  in 
Salisbury,  with  large  veins  of  quartz  in  which  black  tourmaline  crystals 
have  been  collected.  Twenty-nine  small  outcrops  of  this  rock  appear  on 
either  side  of  the  railroad  in  a  distance  of  a  little  over  a  mile,  and  seven 
more  appear  west  of  Town  creek.  Crossing  the  Merrimac  into  Newbury- 
port this  quartz  augite  diorite  was  encountered  nearly  the  whole  length  of 
Market  street,  in  laying  a  sewer  pipe. 

On  High  street,  at  Belleville,  Newburyport,  there  are  ledges  of  this  rock, 
and  on  the  bank  of  the  Merrimac  opposite  Carr's  island,  a  similar  ledge 
was  quarried  for  stone  to  be  used  in  building  the  jetties  and  breakwater 
at  the  mouth  of  the  river.  The  abutments  of  the  famous  Chain  bridge 
across  the  Merrimac  at  Deer  island,  are  also  built  upon  this  quartz  horn- 
blende diorite  rock.     (See  Fig.  49.) 

The  microscopical  structure  of  this  formation  shows  quartz,  plagioclase,  albite, 
Labradorite,  orthoclase,  augite  hornblende  epidote,  calcite,  calcite  titanite,  calcite 
apatite,  and  magnetite.     Uralite  has  been  formed  from  the  decomposition  of  augite 

125 


126  QUARTZ    AUGITE    DIORITE 

biotite.  Chlorite  with  calcite  surround  and  are  intimately  associated  with  the  horn- 
blende areas  as  if  they  were  decomposition  products  of  the  hornblende.  The  rock 
on  the  Salisbury  side  of  the  bridge  is  essentially  the  same. 

Quartz  augite  diorite  is  found  northwest  of  the  Chain  bridge  and 
lying  parallel  to  and  enclosing  a  foliated  mass  of  the  same  structure.  It 
also  is  seen  east  of  the  bridge  and  opposite  Carr's  island  on  the  Salisbury 
side. 

The  microscopical  structure  is  as  follows :  quartz  in  coarse  particles,  numerous 
plagioclase  feldspars,  considerable  calcite,  some  orthoclase,  an  abundance  of  chlorite, 
some  biotite  magnetite,  limonite  magnetite  and  pyrite,  and  numerous  fine  acicular 
crystals  of  rutile  in  the  quartz  and  chlorite.  Small  zircons  as  inclusions  in  the 
biotite  are  abundant.  Uralitization  of  augite  into  uralite  and  actinalite,  with  a 
core  of  augite,  is  common  in  many  parts  of  the  section. 

A  foliated  quartz  hornblende  augite  diorite  found  west  of  the  Chain 
bridge,  has  the  following  microscopical  structure: 

Angular  masses  of  quartz  are  abundant;  some  augite  is  seen  and  rauch  green 
hofnblende  with  broken  and  bent  fragments  of  plagioclase,  feldspar,  biotite ;  some 
muscovite,  magnetite,  cubical  iron  pyrite,  limonite,  chlorite,  calcite,  and  earthy 
kaolin  in  which  there  are  numerous  crystals  of  apatite.  Green  hornblende  and 
angular  fragments  of  quartz,  broken  and  faulted,  are  arranged  in  the  line  of  the 
flow  of  the  rock-mass,  suggesting  that  the  rock  has  been  subjected  to  great  strain 
and  pressure  during  its  consolidation  from  the  magma. 

Thin  sections  of  quartz  hornblende  diorite  from  the  old  quarry  opposite 
Carr's  island  at  Newburyport,  and  from  Salisbury,  give  the  following 
minerals : 

Uralitized  augite  with  occasional  masses  of  typical  augite ;  hornblende ;  biotite ; 
plagioclase  having  the  extinction  angle  of  Labradorite ;  some  orthoclase  and  quartz ; 
an  abundance  of  chlorite ;  considerable  calcite  of  secondary  origin ;  numerous  crystals 
of  apatite  ;  fine  acicular  crystals  of  rutile  ;  large  micro-zircons  ;  iron  pyrites,  and 
magnetite. 

South  of  Little  river  in  Newbury,  other  outcrops  occur  and  frequently 
appear  near  the  Four  Rock  crossing  of  the  railroad.  Extending  south- 
ward to  the  Parker  river  and  including  the  silver  mine  region,  it  is  the 
prevailing  rock.  South  of  the  Newburyport  turnpike,  on  the  right-hand 
side  of  Highfield  street,  there  are  masses  of  dolomitic  limestone  and  a  talc, 
some  of  which  is  of  very  fine  quality  and  is  used  locally  in  place  of  French 
chalk. 


Fig.    65.  — ORDWAY    BOULDER,"  BYFIELD. 
A  glacial    erratic   of  foliated   quartz  hornblende   diorite. 


& 

^ 

1^" 

1 

i 

1 

ffil 

n 

HI 

H^^m 

Fig.   66. —  HAYSTACK    BOULDER,    NEWBURY. 

A  glacial    erratic   of   quartz   hornblende  diorite,  probably  removed  from   the   ledge   six   hundred   feet  distant 

towards  the   north.      A  ten-foot   pole   rests   against  the  boulder. 


HORNBLENDE    DIORITE  129 

Hornblende  Diorite.  —  This  is  found  in  Groveland  and  extends  south- 
ward across  Georgetown  and  Boxford,  where  it  becomes  more  or  less  fo- 
liated and  contains  considerable  quartz.  In  either  massive  or  foliated 
form  it  is  the  prevailing  bed-rock  in  Boxford  (see  Fig.  69)  and  Middleton, 
and  extends  in  a  southwesterly  direction  across  West  Peabody  and  Lynn- 
field  to  Saugus,  where  it  becomes  quite  granitic.  Masses  of  the  latter 
type  are  found  in  the  northeastern  part  of  Lynn  and  Swampscott,  and 
in  Marblehead.  North  from  Swampscott  in  parts  of  Marblehead,  Salem, 
and  Peabody  and  across  Danvers,  the  prevailing  type  is  the  hornblende 
diorite  with  little  or  no  quartz.  (See  Figs.  55,  56.)  There  are  also  five 
distinct  outcrops  in  the  muscovite  biotite  granite  area  in  Andover  and 
North  Andover.  This  rock  formation  is  therefore  about  thirty-two  miles 
long  and  averages  about  six  miles  in  width.  Its  greatest  width,  twelve 
miles,  is  from  North  Andover  across  Boxford  to  Ipswich.  In  part  of  this 
area  the  rock-mass  is  distinctly  an  augite  hornblende  diorite.  This  is 
particularly  well  s-een  at  Marblehead,  near  the  old  fort,  and  on  Gerry's 
island.  In  Danvers  and  Beverly  there  are  numerous  small  porphyritic 
and  pegmatitic  masses  of  this  formation.  At  Putnamville,  Danvers,  folia- 
tion in  these  rocks  has  produced  a  form  which  has  received  the  distinctive 
name  of  amphibolite  gneiss. 

East  of  Ilsley's  hill,  West  Newbury,  there  is  an  outcrop  of  hornblende 
■diorite,  one  half  of  a  mile  wide,  with  numerous  angular  fragments  of  the 
rock  scattered  over  an  area  of  one  quarter  of  a  mile  square.  One  large 
boulder  may  be  seen  at  the  comer  of  Main  and  South  streets.  This  dio- 
rite area  extends  into  Newbury  to  a  point  about  eight  hundred  feet  west 
•of  the  Byfield  railroad  station.  Crane  Neck  hill,  west  of  Ilsley's  hill, 
is  surrounded  by  outcrops  of  this  diorite  which  extend  into  Groveland 
in  this  direction  and  form  the  well-known  boldly  outcropping  ledges  — 
the  "  Nubble  squid."  (See  Figs.  57,  58.)  Hornblende  diorite  also  appears 
■on  Centre  street,  three  quarters  of  a  mile  southwest  from  Cannon  hill. 

A  foliated  quartz  diorite  is  the  prevailing  rock  covering  the  area  from 
Long  hill  in  Georgetown  and  Rowley,  to  Byfield  at  a  point  east  of  the 
Lower  Parish  meeting-house,  and  thence  towards  Newburyport.  South 
■of  Georgetown  this  rock  extends  to  Pye  brook  in  Boxford,  where  outcrops 
occur  in  the  cemetery  east  of  Stevens'  pond  and  also  on  the  grounds  of 
the  Second  Corps  of  Cadets.  An  outcrop  appears  on  the  Rowley  road 
within  two  hundred  yards  of  the  Boxford  railroad  station,  and  others 
•occur  nearly  a  mile  away  between  the  Rowley  and  Georgetown  roads. 
In  this  area  D.  Frank  Harriman  sank  a  shaft  for  silver  ore  to  a  depth  of 


130  HORNBLENDE    DIORITE 

seventy-five  feet,  in  which  the  rock  was  found  to  be  a  typical  quartz 
hornblende  diorite. 

West  of  Hunslow  hill  in  Rowley  there  is  an  outcrop  of  foliated  gneissic 
quartz  diorite  of  the  same  type  as  the  outcrops  at  Long  hill  in  George- 
town. A  mile  north  of  Chaplinville  in  Rowley,  the  Boston  and  Newbury- 
port  turnpike  cuts  through  a  hornblende  diorite  ledge,  and  a  short  distance 
to  the  northward  there  is  a  massive  outcropping  dike  of  aplitic  granite. 
Northeast  from  this  last  outcrop,  on  both  sides  of  Pasture  brook,  south- 
west of  Ox  Pasture  hill,  are  outcrops  of  granodiorite  —  contacts  of  quartz 
hornblende  diorite  and  aporhyolite  ■ —  on  the  north  of  which  is  aplite 
or  vein  granite.  Outcrops  of  a  coarse  felspathic  diorite  appear  north  of 
Jewett's  hill  and  extend  to  Foss'  Comer  and  Bean's  Crossing.  These 
outcrops  are  in  part  hornblende  diorite  nmning  into  quartz  hornblende 
gneissic  diorite. 

The  outcrop  southwest  from  Ox  Pasture  hill  by  the  roadside  opposite  Dole's 
Comer,  is  a  coarsely  crystalline  rock,  the  microscopical  structure  of  which  shows 
large  areas  of  multiple-twinned  Labradorite,  a  little  orthoclase,  green  and  brown 
hornblende,  some  biotite  and  muscovite.  Magnetite  and  chlorite  quartz  appear 
in  the  feldspars.  Zonal  structure  is  often  seen  in  the  Labradorite,  and  prismatic 
sections  of  the  green  hornblende  extinguish  at  8°  to  io°  oblique.  High  double 
refraction  and  fine  twinning  parallel  to  C  is  seen  in  the  Labradorite,  while  apatite 
crystals  are  abundant  as  inclusions  in  the  hornblende.  Calcite  and  chlorite  with 
magnetite  surround  areas  which  formerly  were  hornblende. 

East  of  Hunslow  hill,  Rowley,  is  a  series  of  massive  outcrops  of  horn- 
blende diorite  known  as  "Metcalf  rock,"  which  extends  southerly  into 
Ipswich.  This  diorite  rock  is  also  seen  at  the  southwest  of  Turkey  hill 
and  south  of  Bush  and  Scott's  hills,  near  the  Ipswich  river.  Main  street, 
in  the  center  of  the  village  of  Ipswich,  is  laid  out  over  a  ledge  of  diorite, 
with  dikes  of  diabase,  which  extends  nearly  to  Heartbreak  hill.  There 
are  also  outcrops  of  diorite  on  the  southern  banks  of  Rowley  river  and  on 
the  Ipswich  poor-farm. 

The  outcrops  of  bed-rock  over  the  entire  region  north  of  the  aporhy- 
olite area  in  Byfield  are  quartz  hornblende  diorite  and  hornblende  slate 
with  a  few  areas  of  typical  hornblende  diorite,  which,  near  "the  lime- 
pits,"  pass  into  an  augite  and  diallage  gabbro.  Two  hiindred  yards 
west  of  Cart  creek,  near  the  Copper  mine  opened  by  Luther  Noyes  and  in 
a  quartz  augite  diorite  area,  there  is  a  massive  outcrop  which  is  probably 
a  wide  dike  of  diallage. 


Fig.    67.— A    GLACIAL    ERRATIC    BOULDER    OF    QUARTZ    AUGITE    OIORITE, 
short  distance  from  the   Haystack  boulder,    Newbury.      Length,   28J  feet  and   width   I  8  feet.      Upper 
well  glaciated.     The  nearest   outcrop  of   this  formation  in  the  line  of  glaciation  is  in  Amesbury. 


.  —  FOLIATED    GRANITE    WITH    INCLUSIONS    OF    QUARTZ    DIORITE. 
At  the  base  of    Long   hill,    Boxford. 


HORNBLENDE    DIORITE  133 

The  lime  in  the  old  lime-pits  at  "Devil's  den,"  Newbury  (see  Fig.  60),  is 
without  doubt  a  secondary  deposit  formed  from  the  decomposition  of  the 
augite  and  diallage.  Microscopical  sections  in  polarized  light  show  it  to 
be  an  augite  diallage  peridotite  or  pickrite,  and  not  a  sedimentary  lime- 
stone. The  green  serpentine  of  these  lime-pits  is  another  stage  in  the 
metamorphism  of  the  augite  diallage  rocks  which  must  be  classed  as  a 
pickrite  peridotite. 

The  serpentine  is  usually  massive  and  compact  in  texture,  of  a  dark 
oil,  olive,  or  blackish  green  color,  though  sometimes  a  pale  yellowish 
green.  It  is  also  found  in  a  fibrous  and  lamellar  form  called  chrys- 
otile,  popularly  known  as  asbestus.  It  is  a  metamorphosed  igneous  rock, 
occurring  as  massive  dikes  or  bosses  in  the  hornblende  diorite  or  quartz 
hornblende  diorite  areas.  (See  Fig.  59.)  A  microscopical  study  of  thin 
sections  from  the  "Devil's  den"  and  basin,  in  Newbury,  shows  it  to  be 
composed  originally  of  augite  diallage  olivin  and  hornblende,  probably  an 
ancient  basalt.  The  apparently  pure  white  limestone  (see  Fig.  71)  from 
this  locality  shows  irregular  patches  of  slightly  yellowish  green  serpentine 
with  the  cleavage  of  hornblende.  Outlines  of  augite  crystals  changed  to 
serpentine  are  also  seen.  Olivin  is  sometimes  present  as  a  nucleus.  Some 
sections  contain  olivin  in  which  the  nucleus  is  iron,  and  around  the  olivin 
there  is  a  circle  of  serpentine.  These  changed  minerals  are  known  as 
pseudomorphs,  having  been  derived  from  some  other  species  by  chemical 
change.  The  serpentine  at  South  Lynnfield  is  also  in  the  form  of  a  mas- 
sive dike  cutting  the  hornblende  diorite  of  the  region.  Here  its  color  is 
a  blackish  green  and  in  thin  sections  it  shows  good  basal  cleavage.  Sec- 
tions of  hornblende,  now  turned  to  serpentine,  prove  this  rock  to  be  a 
serpentine  hornblende  pickrite.  This  rock  probably  extends  for  about 
one  half  of  a  mile  in  a  northeasterly  cotirse,  for  a  similar  serpentine  out- 
crops beside  the  road  near  Hersey's  blacksmith  shop  in  West  Peabody. 
The  biotite  mica  peridotite  by  the  side  of  Skug  river  in  Andover,  is  also 
an  altered  serpentinized  olivin  dike-rock.  It  is  a  rare  form  of  rock  and 
is  found  no  where  else  in  the  County. 

When  studied  from  thin  sections  it  is  seen  to  be  composed  of  biotite- 
mica  which  is  bleached  to  a  nearly  white  color,  calcite,  talc,  serpentine, 
and  magnetite  surroxmding  irregular  patches  of  olivin,  which  is  rare,  some 
tremolite  and  a  few  small  masses  of  augite  which  are  also  surrotmded  by 
serpentine.     (See  Fig.  82.) 

A  chemical  analysis  of  the  serpentine  from  the  "  Devil's  den,"  at  New- 
bury, resulted  as  follows : 


134  HORNBLENDE    DIORITE 


Si02 41-33 

FeO 2.36 


MgO 
H,0 


41.49 
14-54 


99.72 


Vesuvianite  occurs  at  Newbury  in  the  old  lime-pits  known  as  the 
"Devil's  den,"  where  it  is  quite  massive  and  somewhat  crystalline.  Thin 
sections,  cut  in  the  line  of  its  optic  axis,  give  exceedingly  brilliant  polariza- 
tion colors  with  high  double  refraction ;  so  also  do  sections  parallel  to  the 
prism  and  parallel  to  the  pyramid.  The  specific  gravity  is  3.60.  The 
following  analysis  was  made  by  James  T.  Greeley  of  the  Massachusetts 
Institute  of  Technology/ 

SiOj 35-93 

MO3 14-77 

FeO 8.91 

CaO 39-46 

MgO 13 

K2O 44 

NajO 36 


Crane  Neck  hill,  a  large  drumlin  in  West  Newbury,  is  surrounded  by 
outcrops  of  hornblende  diorite  which  extend  into  Groveland  and  George- 
town.    The  rock  at  Groveland  is  a  form  of  quartz  hornblende  diorite. 

The  well-known  Stickney  boulder  near  Centre  street  in  Groveland 
(see  Fig.  61),  is  a  mass  of  hornblende  diorite  resting  upon  a  bare  ledge  of 
the  same  rock.  The  base  of  this  boulder  is  roughly  rectangular  and 
measures  27  feet  by  18  feet.  The  height  averages  14  feet  and  therefore 
gives  6,804  cubic  feet  of  contents.  The  specific  gravity  is  3.375,  and  a 
cubic  foot  accordingly  weighs  211  pounds,  giving  a  total  weight  of  about 
718  tons.^  In  the  immediate  region  are  other  large  boulders  known  as 
Split  rock  (see  Fig.  62),  Cradle  rock  (see  Fig.  64),  and  Norseman's  rock,  a 
large  outcrop  of  quartz  hornblende  diorite  (see  Fig.  63). 

In  West  Newbury,  on  the  J.  B.  Little  road,  there  is  an  outcropping 
ledge  of  diorite  with  veins   of  quartz.     "Nubble  squid"   or   "Knubble 

'  See  Massachusetts  Institute  of  Technology  Quarterly,  May,  1888. 
'  See  Hitchcock's  Geology  of  Massachusetts,  page  373,  where  the  weight  of  the  rock  is 
estimated  to  be  about  2,310  tons. 


-MASSIVE    AND    FOLIATED    QUARTZ    HORNBLENDE    DIORITE    OUTCROP    WITH 
INTRUSIONS    OF    COURSE    VEIN-GRANITE. 
Lovering's   mountain,    Boxford. 


Fig.   70.— HORNBLENDE    DIORITE    AT    LEDGE    HILL    PARK,    SALEM 
Showing  glaciated  surface. 


HORNBLENDE    DIORITE  137 

squid ' '  — ■  either  name  is  of  doubtful  origin  —  is  a  large  outcrop  of  horn- 
blende diorite  or  trap-rock  (see  Fig.  57),  in  the  southeastern  part  of 
Groveland,  extending  across  West  Newbury  into  Newbury  and  George- 
town. These  hornblende  diorite  rocks  have  a  tendency  to  run  into  the 
quartz  diorite  of  Newbury  to  such  an  extent  that  they  may  be  considered 
as  parts  of  one  and  the  same  rock,  although  separate  from  the  quartz 
augite  diorites  of  the  Newburyport,  Salisbury,,  and  Amesbury  area.  These 
hornblende  diorites  are  thoroughly  granitic  in  type,  and  but  for  the  amounts 
of  augite  and  plagioclase  in  some  parts  of  the  area,  would  be  classed  as  a 
form  of  augite  granite;  in  fact,  some  outcrops  contain  a  large  proportion 
of  augite  with  little  or  no  orthoclase.  Uralite  has  replaced  the  augite. 
and  calcite  has  been  developed.  All  of  the  outcrops  from  Georgetown  to 
West  Newbury,  on  either  side  of  the  J.  B.  Little  road  and  as  far  as  the 
Seven  Star  road  in  Groveland,  are  hornblende  and  quartz  hornblende 
diorite,  and  at  the  westward,  on  either  side  of  the  railroad,  are  other 
massive  outcrops,  a  southwestern  continuation  of  the  "  Nubble  squid." 

The  foliated  quartz  diorite  of  Long  hill,  Georgetown,  extends  across 
Newbury  and  Rowley  to  an  outcrop  west  of  Hunslow  hill.  On  the  north- 
east it  is  cut  by  the  rhyolites  from  Newbury  Old  Town,  beyond  which  it 
is  the  bed-rock  of  the  mining  area  in  Newbury.  Resting  upon  this  rock 
are  glacial  erratics  —  diorite  boulders  of  considerable  size.  On  the  south 
side  of  Parker  street,  Groveland,  is  the  Ordway  boulder  (see  Fig.  65), 
the  "Haystack"  (see  Fig.  66),  and  a  large  boulder  of  quartz  augite  diorite. 
At  the  base  of  Long  hill,  Boxford,  the  outcropping  ledge  is  a  massive 
quartz  diorite,  including  blocks  of  gneissic  hornblende  diorite.  (See  Fig. 
68.)  Here  the  magma  flowed  partially  in  straight  lines  and  also  became 
variously  folded  and  crumpled,  enclosing  the  blocks  and  strings  of  the 
older  diorite.  Northeast  of  Long  hill  is  a  high  outcrop,  known  as  Lover- 
ing's  moxintain.  Here  the  foliated  quartz  hornblende  diorite  is  cut  by 
veins  of  aplite  granite.  (See  Fig.  69.)  The  hornblende  diorite  northeast 
of  Bald  Pate  pond  is  a  segregation  of  basic  minerals  in  the  foliated  quartz 
diorite  series  and  judging  from  the  number  of  the  outcrops  further  to  the 
northeast,  the  Rowley  and  Newbury  area  must  have  been  the  principal 
mass,  which,  flowing  southwesterly,  was  erupted  into  the  hornblende 
epidote  gneiss  and  sedimentary  beds  of  the  Georgetown,  Groveland,  Box- 
ford,  and  Topsfield  area.  These  quartz  diorites,  when  massive,  with 
slight  change  in  the  mineral  constituents,  become  locally,  granites  —  vein- 
granites  or  aplites,  foliated  quartz  hornblende  diorites,  and  sometimes 
granodiorites,  as  in  the  area  south  of  Ox  Pasture  hill  in  Rowley. 


138  HORNBLENDE    DIORITE 

The  finest  outcrops  are  to  be  found  at  Middleton,  Boxford,  Georgetown,  Byfield, 
and  the  Newbury  mining  region.  The  microscopic  structure  of  sections  of  a  speci- 
men from  Middleton  gave :  quartz  in  grains  and  patches ;  plagioclase  with  numerous 
inclusions  of  quartz ;  biotite  and  epidote ;  green  hornblende  with  inclusions  of  biotite 
and  apatite  crystals;  some  titanite  and  chlorite;  ground-mass  of  secondary  quartz 
and  ferrite.  Sections  from  Boxford  exhibited  numerous  quartz  grains,  well-rounded 
plagioclase  grains,  much  orthoclase  deeply  kaolinized,  both  the  plagioclase  and  the 
orthoclase  having  numerous  inclusions  of  quartz  and  biotite.  There  were  also 
grains  of  epidote  and  fine  dust-like  ferrite,  and  muscovite  plates  arranged  parallel 
to  the  bedding.  The  microscopic  structure  of  a  section  from  John  Noyes'  copper 
mine  in  Newbury,  closely  resembled  the  sections  from  Boxford,  excepting  that 
there  was  more  biotite,  that  numerous  cubes  of  iron  pyrite  were  scattered  through 
the  dust-like  ferrite,  and  that  microliths  were  of  numerous  occurrence. 

At  the  comer  of  School  and  Liberty  streets  in  Middleton,  there  is  a 
massive  outcrop  of  typical  hornblende  diorite,  the  microscopical  structure 
of  which  is:  brown  hornblende,  albite,  Labradorite,  biotite,  magnetite, 
apatite,  and  a  little  calcite.  The  minerals  show  little  sign  of  decay,  in 
fact,  the  rock-mass  is  remarkably  tough  and  fresh.  The  occurrence  of 
calcite  in  the  section  is  difficult  to  explain.  North  of  WiUdns'  hill.  Middle- 
ton,  are  two  outcrops  of  hornblende  diorite,  and  across  the  river  in  Tops- 
field  and  Boxford  there  are  frequent  outcrops,  together  with  quartz  horn- 
blende diorite.  At  Bald  hill,  Boxford,  this  quartz  diorite  is  massive  and 
also  foliated,  one  form  running  into  the  other  in  every  sixth  of  a  mile. 
North  of  the  hill  and  directly  at  its  base  is  a  fine  example  of  foliation  from 
the  massive  rock.  From  this  point  as  far  as  the  Boxford  match  factory 
and  easterly  nearly  to  Boxford  village,  the  foliated  rock  is  in  excess  of 
the  massive  form.  The  foliated  or  gneissic  diorite  or  granite,  can  always 
be  traced  directly  to  the  massive  rock.  It  is  therefore  plain  that  all  the 
granitic  gneisses  are  merely  foliated  forms  of  the  massive  rocks,  due  to 
the  flow  of  the  magma  caused  by  lateral  or  other  pressure  previous  to  its 
consolidation.  A  microscopical  comparison  of  the  quartz  hornblende 
diorite  in  the  Middleton  and  Boxford  areas,  shows  foliation  and  crumpling 
to  be  the  only  differences  existing  between  this  rock  and  the  quartz  horn- 
blende gneiss.  The  microscopical  structure  of  numerous  thin  sections 
shows  them  to  be  composed  essentially  of  the  same  minerals. 

A  section  from  an  outcrop  north  from  Middleton  near  the  railroad,  had  the  fol- 
lowing structure  :  quartz,  albite,  and  Labradorite  ;  some  orthoclase  in  simple-twins; 
brown  hornblende  biotite,  titanite,  epidote,  calcite,  magnetite,  and  limonite,  with 
apatite  crystals  in  the  quartz.  Large  crystals  of  titanite  are  common.  Another 
outcrop  gave  quartz,  augite,  diorite,  and  brown  hornblende,  paramorphic  of  augite, 


Fig.  7  1.  — PHOTOMICROGRAPH    OF    WHITE    LIMESTONE,    SHOWING    SERPENTINE    PSEUDOMORPHS, 
DEVIL'S   DEN,    NEWBURY. 


Fig,   72   —PHOTOMICROGRAPH    OF    A    BIOTITE    CONCRETION    IN    MICA    HORNBLENDE 
DIORITE    AT  MIDDLETON. 


HORNBLENDE    DIORITE  141 

augite  crystals,  much  biotite,  albite,  and  Labradorite,  feldspars  finely  twinned  and 
quite  fresh,  some  orthoclase  mostly  altered  to  saussurite,  and  kaolin  colored  by 
limonite.  In  the  hornblende  and  augite  there  was  some  chlorite  and  epidote. 
A  quartz  vera  four  inches  wide  cuts  through  this  outcrop. 

In  1904,  an  electric  railway  cut  the  following  interesting  section 
across  the  towns  of  Middleton  and  North  Andover,  following  the  line  of 
the  old  turnpike.  The  first  ledge  encountered  north  of  Boston  brook  was 
a  foliated  quartz  hornblende  diorite;  the  second,  a  hornblende  diorite 
with  little  or  no  quartz  and  cut  by  veins  of  hornblende  granite.  From 
this  outcrop  all  others  to  the  North  Andover  town  line  were  quartz  horn- 
blende diorite.  The  first  outcrop  in  North  Andover,  opposite  the  house  of 
Daniel  Berry,  was  a  very  basic  hornblende  diorite  of  the  type  known  as 
monzonite,  having  long  veins  and  masses  of  white  quartz.  These  diorite 
ledges  were  easily  traced  in  an  easterly  direction  across  Boston  brook 
to  the  massive  outcrops  previously  mentioned  in  the  Middleton,  Topsfield, 
and  Boxford  area.  On  the  south  and  west  these  formations  were  traced 
into  North  Reading.  The  quartz  diorites  also  appeared  about  the  base 
of  Will's  hill,  Middleton,  and  extended  to  Forest  lake  and  nearly  to  the 
Middleton  paper  mill.  West  of  the  hill,  a  series  of  granite  veins  cut 
through  the  diorite  rocks.  This  granite  is  locally  known  as  "Swan  Pond 
granite,"  it  having  its  greatest  development  on  the  shore  of  this  pond. 
About  Martin's  pond  the  veins  and  tongues  of  this  granite  cut  through 
the  diorite  in  all  directions.  At  Forest  lake,  it  is  a  vein  of  coarse  mica- 
ceous aplite  granite,  the  microscopical  structure  of  which  is  as  follows : 

Much  orthoclase,  some  of  which  is  twinned  as  in  the  Carlsbad  type,  shows  the 
basal  and  second  cleavage  very  perfectly,  but  the  whole  section  has  a  strained 
appearance.  In  one  plate  of  this  feldspar  a  shadow  appears  as  the  plate  is  re- 
volved on  the  stage  of  the  microscope,  and  does  not  extinguish  properly.  There 
are  fine  plates  of  microcline.  The  quartz  seen  in  rods  and  grains  of  irregular 
form  resembles  graphic  granite.     Hornblende  and  biotite  are  rarely  found. 

West  of  the  lake  this  granite  outcrops  in  both  large  and  small  masses, 
having  blocks  of  hornblende  diorite  and  quartz  hornblende  diorite  held 
as  inclusions.  Some  of  the  outcrops  are  a  complete  breccia  of  the  diorite 
with  the  granite  on  all  sides  of  the  brecciated  parts.  From  here  the 
granite  and  diorite  extend  a  distance  of  three  miles,  nearly  to  the  Ingalls' 
Crossing  railroad  station,  where,  towards  the  northeast,  the  diorite  becomes 
a  mica  hornblende  diorite  containing  biotite  mica  concretions  (see  Fig. 
72),  and  in  a  more  northerly  direction  is  cut  off  from  the  Andover  region, 


142  HORNBLENDE    DIORITE 

except  as  included  masses  in  the  muscovite  biotite  granite  which  sur- 
rovinds  the  diorite  areas. 

On  the  Ipswich  Beach  road,  near  the  comer  of  the  Essex  road,  diorite 
appears  above  the  surface  and  other  outcrops  occur  on  the  north  side  of 
Beach  street  and  also  in  Hamilton,  near  Miles  river.  The  Beverly  end 
of  Folly  hill  is  diorite,  which  extends  on  both  sides  of  Bass  river  towards 
Hamilton  and  also  towards  North  Salem.  The  diorite  shows  outcrops 
on  the  southwesterly  shore  of  Wenham  lake,  and  the  Boston  and  Maine 
railroad  cuts  through  a  ledge  which  extends  to  Larch  street  in  Wenham. 

The  outcropping  bed-rock  in  Salem,  west  of  Salem  Neck,  is  hornblende 
diorite  without  quartz,  a  fine  homogeneous  basic  rock,  cut  by  veins  of 
aplitic  granite  and  narrow  dikes  of  pulaskite  syenite  with  little  or  no 
hornblende.  Castle  hill,  Legg's  hill  (see  Fig.  73),  Lookout  hill,  and  Ledge 
Hill  park,  are  elevations  of  90  to  160  feet  above  mean  sea-level,  and  are 
entirely  diorite  with  a  scanty  covering  of  soil.  In  North  Salem  there  are 
numerous  outcrops  of  hornblende  diorite.  Buxton's  hill  in  Peabody  is 
formed  of  this  rock.'  Mount  Pleasant  at  Proctor's  Crossing  is  a  ridge  of 
diorite,  which  extends  in  a  northwesterly  direction  for  about  two  miles. 
The  diorite  at  Danvers  Centre  is  the  quartz  hornblende  diorite  from  Mid- 
dleton,  in  which  there  are  areas  showing  a  gneissic  foliated  form. 

On  Chestnut  street,  Lynnfield  Centre,  there  is  an  outcrop  of  horn- 
blende diorite,  and  an  eighth  of  a  mile  distant  is  the  Tophet  Hill  gold  mine, 
a  diallage  gabbro  dike  cutting  through  diorite.  At  the  contact,  the  rock 
contains  pyrite,  micaceous  hematite,  galena,  and  fluorite.  Near  C.  W. 
Hersey's  blacksmith  shop,  a  mile  from  here,  there  is  an  outcrop  of  serpen- 
tine peridotite,  and  outcrops  of  this  rock  occur  near  the  railroad  one  third 
of  a  mile  to  the  south.  A  fourth  of  a  mile  east  from  the  railroad  station 
there  is  a  hill  of  hornblende  diorite  with  a  wide  dike  of  diallage  gabbro 
cutting  through  the  diorite.  Directly  to  the  north,  in  the  woods  beyond 
Pine  hill,  are  outcrops  of  hornblende  granite,  an  aplitic  form,  in  a  long 
ridge  that  is  probably  a  dike.  This  ledge  is  locally  known  as  Harris' 
rock.  Southeast  of  Walden  hill  and  near  the  town-line  between  Peabody 
and  Lynnfield  there  is  another  outcrop  of  hornblende  diorite.  South 
from  Proctor's  Crossing,  outcrops  of  hornblende  granite  extend  to  the 

1  An  interesting  dike,  a  minette  form  of  lamphrophyre  closley  related  to  the  augite 
syenite,  cuts  across  the  hill  at  the  south  and  southeast.  The  composition  of  this  dike 
rock  is  orthoclase,  feldspar,  augite,  biotite,  and  magnetite,  while  the  accessory  minerals 
are  zircons,  apatite,  albite,  calcite,  and  uralite.  This  is  the  only  minette  dike  rock  thus 
far  recorded  in  the  County. 


Fig.    73.— LEGG'S    HILL,    SALEM,    A    DIORITE    LEDGE    WITH    SUMMIT    GLACIATED 

AND    STRIPPED    OF    DEBRIS. 

Kame    topography  and   washed  gravels  shown   in  the  foreground. 


Fig,    74.  — QUARTZ    HORNBLENDE   DIORITE    OUTCROP   AT    CLIFTON,    SHOWING 

BROKEN    AND    BIZARRE    FORM    OF    HEADLAND. 

Marblehead   Neck  in  the  distance. 


HORNBLENDE    DIORITE  145 

Jacob  C.  Rogers'  estate  and  easterly  to  the  western  part  of  Buxton 's  hill. 
Veins  of  the  Mount  Pleasant  granite  extend  northward  into  Dan  vers. 

In  Peabody,  about  two-thirds  of  a  mile  from  the  Salem  boundary,  there 
is  a  series  of  outcrops  of  hornblende  granite  in  contact  with  the  Salem  horn- 
blende diorite,  where  veins  and  massive  tongues  of  the  granite  are  intru- 
sive in  the  diorite  rock,  and  many  areas  of  micrographic  granite  may  be 
seen  near  the  contact  of  the  granite  and  diorite.  There  are  no  intrusive 
veins  or  dikes  in  the  granite,  for  the  hornblende  granite  is  the  j^ounger 
rock  and  cuts  the  older  diorite.  No  other  example  has  been  found  in 
the  Cotmty  where  both  forms  are  massive  at  a  contact  and  where  the 
actual  contact  is  so  well  illustrated. 

On  the  high  land  of  the  Governor  Endicott  farm  at  Danversport,  there 
is  a  massive  outcrop  of  hornblende  diorite,  which  is  also  the  bed-rock 
tmder  the  clay-beds  at  the  west  side  of  the  hill.  The  diorite  also  outcrops 
on  the  north  side  of  Lindall  hill,  and  from  Stunmer  street  across  Putnam- 
ville  to  West  Wenham  there  are  numerous  other  outcrops. 

Gradual  transitions  from  massive  hornblende  diorite  to  amphibolite 
gneiss  may  be  seen  on  a  large  scale  in  a  railroad  cut  north  of  the  Putnam- 
ville  station,  and  also  at  Danvers  Centre  near  the  corner  of  Newbmy  and 
Dayton  streets.  In  these  diorite  masses  the  minerals  are  elongated  and 
secondary  feldspars  and  calcite  are  developed  in  lines  and  around  small 
masses  of  hornblende  and  magnetite.  The  latter  is  largely  changed  to 
hematite  and  limonite  which  gives  the  rock-mass  a  decidedly  gneissic 
appearance,  but  it  does  not  in  the  least  resemble  the  hornblende  epidote 
gneiss  which  only  occurs  in  regions  of  granitic  rocks.  Another  area  of 
this  foliated  diorite  may  be  seen  by  the  roadside  at  Putnamville  near  the 
Wenham  line.  The  diorite  of  the  entire  Putnamville  area  is  cut  by  veins 
or  narrow  dikes  of  aplitic  granite,  and  wherever  the  diorite  rock  occurs  in 
massive  form,  some  part  of  the  area  will  be  seen  to  be  gneissic,  due  to  the 
flow  of  the  diorite  magma  previous  to  its  consolidation. 

West  of  Hawkes'  brook  in  Peabody,  the  railroad  cuts  through  a  hill  of 
quartz  hornblende  diorite  which  extends  into  Saugus  with  one  outcrop 
on  the  east  side  of  Hawkes'  pond,  half  a  mile  south  of  the  railroad  track. 
This  diorite  also  appears  on  both  sides  of  Hewlett's  brook,  and  from  the 
north  and  westerly  sides  of  Breakheart  hill  in  Saugus,  it  continues  into 
Middlesex  County.  Between  Little  Castle  hiU  and  Breakheart  hill  the 
quartz  diorite  outcrops,  and  southeasterly  one  half  a  mile  across  Main 
street  are  six  outcrops  extending  into  Melrose.  Frequent  outcrops  of 
quartz  diorite  appear  at  the  northwesterly  end  of  Walden  pond,  on  the 


146  HORNBLENDE    DIORITE 

entire  easterly  side  of  Pranker's  pond,  and  at  the  western  end  of  Glen  Lewis 
pond.  On  the  southern  side  of  Glen  Lewis  pond,  stand  Mount  Gilead 
and  Burrill  hill,  both  outcrops  of  a  very  granitic  quartz  granodiorite  rock. 
Some  of  the  rock-sections  from  Mount  Gilead  are  very  near  a  true  horn- 
blende granite,  orthoclase  being  in  excess.  Other  sections  show  triclinic 
feldspars  in  excess  of  orthoclase. 

Baker's  island,  in  Salem  harbor,  is  a  massive  outcrop  of  quartz  diorite, 
a  tonolite  or  vein-rock  mass  of  two  forms.  The  ledges  on  the  west  and 
northwestern  part  of  the  island  are  a  fine-grained  highly  mineralized  rock 
having  numerous  small  quartz  veins,  while  the  outcropping  rock  on  the 
central  and  eastern  portions  of  the  island  is  a  coarser  form  with  much 
hornblende  and  biotite.  A  wide  vein  of  milky  quartz  may  also  be  seen 
on  the  northeastern  part  of  the  island.  This  coarse  quartz  diorite  is 
cut  by  a  wide  porphyritic  diabase  dike  running  across  the  island  from 
east  to  west,  and  a  number  of  smaller  dikes  cut  the  island  from  north  to 
south.  One  large  hornblende  olivin  basalt  dike,  cutting  through  the 
island  from  the  southwest  to  the  northeast,  is  the  same  rock  as  the  Pope's 
head  formation,  and  also  a  part  of  Eagle  island  of  which  the  principal 
mass  is  quartz  diorite.  In  a  southwesterly  course  this  rock  forms  out- 
crops at  Peach's  point,  on  the  shore  of  Marblehead,  at  Ome's  island, 
Gerry's  island,  the  headland  on  which  Fort  Sewall  is  built,  and  also  on  the 
headland  beyond  Deveretix  beach.  Small  dikes  and  veins  of  this  quartz 
tonolite  diorite  cut  the  hornblende  diorite  and  the  hornblende  granite  at 
Devereux  and  Clifton,  and  may  be  observed  in  several  cuts  along  the  line 
of  the  railroad. 

Little  Misery  island,  having  an  area  of  three  acres,  is  an  outcrop  of 
hornblende  gabbro,  with  a  small  outcrop  of  quartzite  near  the  channel 
which  separates  the  island  from  the  Great  Misery.  Probably  other  sedi- 
mentary rock  in  the  bottom  of  the  channel  would  account  for  the  line  of 
weakness  which  permitted  the  sea  to  form  this  passage.  On  the  southern 
and  eastern  side  of  Great  Misery,  cliffs  rise  very  abruptly  to  a  height  of 
thirty  feet,  and  are  deeply  cut  by  dikes  which  the  sea  has  removed,  leaving 
steep-sided  cuts  extending  into  the  shore  of  the  island. 

The  bed-rock  of  Marblehead  is  largely  hornblende  diorite  with  massive 
dikes  of  basalt  and  diabase.  (See  Fig.  74.)  Numerous  outcrops  occur  in 
the  central  part  of  the  town  and  on  the  seashore  near  Bass  rocks.  The 
whole  diorite  area  is  in  part  brecciated  by  syenite  and  aplite  veins,  which 
may  be  observed  in  road-cuttings  and  other  deep  cuts  m  all  parts  of  the 


Fig.  75.— HORNBLENDE  GRANITE  QUARRY  AT  ROCKPORT. 

Showing  jointing  of  tile   formation. 


Fig.    76.  — HORNBLENDE    GRANITE    QUARRY    AT    LANESVILLE,   GLOUCESTER. 
Showing  gradual  increase  in  thickness  of  the  joint  planes. 


HORNBLENDE    DIORITE  149 

town.     On  the  shore  at  CHfton  the  quartz  diorite  rocks  are  cut  by  dikes 
of  apHtic  granite. 

The  following  cuttings,  which  may  be  taken  as  typical  of  the  whole  series,  have 
microscopical  structures  as  follows  : 

No.  I.  Jersey  street,  augite  diorite  :  Augite,  hornblende,  orthoclase,  plagioclase,, 
biotite,  magnetite,  quartz,  apatite,  micro-zircons,  and  some  garnets.  The  quartz 
is  apparently  original  as  it  has  inclusions  of  zircons  and  apatite. 

No.  2.  Abbot  street,  augite  diorite:  This  has  more  orthoclase  and  large  masses 
of  apatite  crystals  in  both  the  orthoclase  and  plagioclase;  otherwise  as  in  No.  i. 

No.  3.  Abbott  street,  augite  diallage  diorite  gabbro  :  Large  masses  of  augite, 
some  diallage,  green  hornblende,  biotite  and  drusy  quartz,  masses  of  large  micro- 
apatite  crystals,  some  zircons,  a  little  apatite,  plagioclase  somewhat  kaolinized,  and 
a  little  orthoclase.  The  biotite  is  of  the  red  color  so  noticeable  in  the  elseolite  zircon 
syenite.     Some  of  the  augite  is  seen  as  inclusions  in  the  hornblende. 

No.  4.  Jersey  street,  augite  olivin  hypersthene  diorite  gabbro  :  This  rock  is 
perfectly  fresh,  no  decomposition  being  noticeable  in  any  of  the  minerals.  The 
probable  genesis  of  the  crystallization  of  these  minerals  from  the  magma  was 
magnetite,  zircon,  apatite,  augite,  olivin,  hypersthene,  biotite,  hornblende,  plagio- 
clase, orthoclase,  and  quartz. 

East  of  the  Andover  Theological  Seminary  there  is  an  outcrop  of 
the  hornblende  diorite  known  as  Rabbit  rock.  Other  outcrops  extend 
northerly  from  this  point  to  Clay  Pits  hill,  a  distance  of  about  one  mile. 
East  of  this  line  of  outcrops  may  be  found  the  mica  granite  of  North 
Andover.  The  diorite  outcrops  in  the  Andover  region  have  numerous 
veins  and  large  dikes  of  fine  mica  granite  cutting  through  them,  and  in 
the  foliated  parts  of  the  granite  there  are  masses  and  blocks  of  diorite 
and  slate  held  as  inclusions,  indicating  that  the  older  bed-rock  of  this 
area  was  the  basic  hornblende  diorite  which  has  since  been  cut  by  the 
micaceous  granite.  Near  the  Andover  almshouse  there  is  an  outcrop  of 
hornblende  diorite,  which  is  fifteen  hundred  yards  in  length  and  about 
three  hundred  yards  in  width,  and  east  of  this  area  across  the  Andover 
turnpike  is  a  small  outcrop  of  the  muscovite  biotite  granite.  West  of 
Stevens'  woolen  mills,  and  in  a  northeasterly  direction  from  Indian  ridge, 
occurs  a  massive  outcrop  of  typical  hornblende  diorite  which  extends 
nearly  to  the  bank  of  the  Shawsheen  river.  Six  outcrops  of  hornblende 
diorite  appear  on  the  eastern  side  of  Carmel  hill.  Contacts  of  these  rock 
formations  are  not  exposed. 


CHAPTER  V 

HORNBLENDE    GRANITE 

This  name  is  given  to  the  granite  rocks  of  Cape  Ann  and  the  eastern 
part  of  the  County.  Under  the  general  type  there  are  several  varieties, 
either  coarse  or  fine  grained,  and  containing  little  or  much  biotite.  The 
Peabody  and  Lynnfield  granites  contain  little  biotite,  while  in  the  Glouces- 
ter and  Rockport  granites  (see  Fig.  75)  there  is  much  biotite.  There  are 
also  local  variations  in  color  due  to  inclusion  of  other  minerals  in  the 
feldspars.  The  Pigeon  hill  and  Lanesville  granites  (see  Fig.  76)  are  of  a 
greenish  color,  while  the  granite  from  Wenham  and  Ipswich  is  grayish 
white.  In  a  few  areas  the  quartz  is  in  excess,  while  in  others  there  is  little 
quartz  and  that  is  of  a  smoky  color.  Examples  of  this  are  seen  in  the 
upper  opening  of  the  Rockport  Granite  Company's  quarry  at  Rockport. 

From  an  economic  point  of  view  the  hornblende  granite  is  the  most 
valuable  rock  formation  in  the  County.  The  perfect  rift  and  cut-off  per- 
mit the  rock  to  be  easily  worked  into  a  commercial  stone  of  pronotmced 
durability  for  building  and  bridge  work.  Its  susceptibility  of  receiving  a 
good  polish  makes  it  desirable  for  interior  construction  and  also  for  cem- 
etery work. 

Thin  sections  of  this  hornblende  granite  when  studied  with  the  microscope, 
show  it  to  be  composed  of  the  following  minerals:  orthoclase,  microcline,  micro- 
perthite,  which  is  composed  of  simple-twinned  albite  crystals  intergrown  across  the 
twinning  plane  of  the  microcline ;  hornblende  of  the  green  variety,  sometimes  altered 
to  glaucophane;  much  quartz  and  biotite;  with  fluorite,  garnets,  zircons,  actinolite, 
and  magnetite  as  accessory  minerals  in  the  feldspars.  Nearly  all  of  the  rocks  of 
this  formation  show  evidence  of  subjection  to  a  great  strain  or  crushing  force,  as 
most  of  the  original  minerals  have  numerous  cracks  which  have  been  filled  with  a 
secondary  formation,  either  biotite  or  glaucophane. 

Minerals  in  the  thin  sections  from  the  Cape  Ann  Granite  Company's  quarries 
at  Rockport,  are  as  follows :  quartz  in  large  patches,  which  is  greatly  cracked  and 
crushed,  orthoclase,  microcline,  some  plagioclase,  microperthite,  hornblende,  a 
little  biotite,  some  muscovite,  large  patches  of  magnetite,  some  microscopic 
zircons  of  considerable  size  and  epidote  and  limonite.  The  feldspars  are  much 
decomposed.  This  section  is  nearly  identical  with  sections  of  the  same  rock  from 
Wenham,  Hamilton,  and  Ipswich. 

150 


Fig.   77.— RACCOON    ROCKS,    MANCHESTER. 
An  outcropping  ridge  of  hornblende  granite. 


Fig.   78.— HORNBLENDE    GRANITE    OUTCROP    IN    THE    RACCOON    ROCKS,    MANCHESTER. 


HORNBLENDE    GRANITE  153 

The  microscopical  structure  of  other  sections  of  this  rock  taken  from  the  Cape 
Ann  Granite  Company's  quarry  at  Bay  View,  is  as  follows:  quartz  in  large  patches; 
orthoclase,  much  of  which  is  in  simple  twins  after  the  Carlsbad  type ;  multiple-twinned 
plagioclase;  probably  anorthite;  some  basal  sections  of  microcline;  green  hornblende; 
some  biotite  and  muscovite ;  much  magnetite,  with  numerous  micro-zircons  of  con- 
siderable size  held  as  inclusions  in  the  biotite  and  orthoclase.  Part  of  the  multiple- 
twinned  plagioclase  is  clearly  albite.  In  some  sections  there  are  fine  examples  of 
microperthite  — •  intergrowths  of  albite  and  orthoclase.  All  of  the  quartz  masses 
show  incipient  cracks,  and  in  some  cases  they  are  broken.  Near  these  quartz  areas 
the  feldspars  are  somewhat  decomposed. 

There  are  several  distinct  areas  of  this  formation.  The  Saugus  area 
is  nearly  continuous  east  and  west  from  the  Pig  rocks,  off  the  Swampscott 
shore,  to  North  Saugus.  From  Moimtain  street  in  Lynn,  to  near  Vinegar 
hill,  it  is  cut  by  rhyolites,  and  at  North  Saugus  it  is  cut  by  quartz  augite 
syenite  extending  from  the  Lynnfield  area.  The  Lynnfield  and  Peabody 
granite  reaches  westerly  to  Proctor's  Crossing,  northerly  to  Danvers,  and 
southeasterly  to  Marblehead  neck  and  Tinker's  island,  where  it  is  separated 
from  the  main  mass  on  Marblehead  and  Marblehead  neck  by  rhyolites.  An- 
other area  is  central  in  Danvers  and  East  Wenham,  and  extends  westerly 
to  the  Danvers  and  Topsfield  town  lines,  northerly  to  the  village  of  Topsfield, 
and  easterly  across  Wenham  and  Hamilton  to  Ipswich.  This  area  is  cut 
by  quartz  augite  syenites  in  East  Wenham,  and  Hamilton  and  between 
Hamilton,  Ipswich,  and  Essex.  Another  area  is  between  Bass  river, 
Beverly,  and  Rockport,  and  presents  an  almost  continuous  series  of  out- 
crops cut  occasionally  by  the  quartz  augite  syenites,  nordmarkite,  and 
pulaskite  syenites.  The  whole  of  this  area  is  cut  by  numerous  narrow 
basic  dikes. 

The  hornblende  diorites  which  extend  across  Marblehead,  Salem,  Pea- 
body,  and  Danvers,  are  cut  by  the  granites  at  every  contact  that  has  been 
found,  and  as  masses  of  diorite  exist  between  most  granite  formations, 
they  must  be  considered  as  distinct  masses  of  granite.  The  microscopical 
structure  of  these  various  granite  masses  shows  variation  but  not  enough 
to  create  distinct  forms.  The  trend  of  the  whole  series  is  approximately 
northeast  to  southwest,  but  the  trend  of  the  outcrops  of  the  individual 
mass  is  usually  east  and  west,  or  north  and  south. 

East  of  Wenham  lake,  the  hornblende  granite  outcrops  on  Dodge 
street.  North  Beverly,  on  both  sides  of  Norwood's  pond,  and  on  the  north 
side  of  Brimble  hill.  South  from  this  hill  and  extending  to  Montserrat 
and  to  the  city  of  Beverly,  is  a  series  of  hornblende  granite  outcrops,  one 
of  which  is  the  elevation  on  which  the  Salem  reservoir  is  built.     It  also 


154  MICROGRAPHIC    GRANITE    OR    GRANOPHYRE 

appears  at  the  comer  of  Bomer  and  Maple  streets,  West  Wenham,  and 
extends  into  the  northern  part  of  Dan  vers,  and  is  also  found  in  the  valley 
between  Pingree's  and  Towne's  hills  in  Topsfield.  On  both  sides  of  Nichols' 
brook  in  Topsfield,  there  are  five  outcrops  of  the  red  granite,  boulders  of 
which  are  so  often  seen  in  the  boulder-till  of  Danvers  and  Beverly.  One 
outcrop  is  quite  massive  and  stands  at  an  elevation  of  one  hundred  and 
twenty  feet.  In  Middleton,  on  the  south  side  of  this  brook,  appear  outcrops 
of  hornblende  granite,  and  across  the  Ipswich  river  is  Oak  hill,  a  massive 
outcrop  having  an  elevation  of  one  hundred  and  forty  feet.  In  West  Box- 
ford,  north  of  the  village,  are  outcrops  which  connect  with  the  large  ex- 
posure at  Lakeside  farm  beside  Johnson's  pond.  This  granite  is  probably  a 
vein  or  tongue  from  the  North  Andover  area  intruded  into  the  old  Cam- 
brian sedimentary  beds.  At  Groveland,  near  the  railroad,  there  are  several 
outcrops  of  this  hornblende  granite  of  a  foliated  or  gneissic  formation. 

Hornblende  granite  is  found  at  Ipswich,  about  Heartbreak  hill,  and  on 
a  small  island  in  the  tidal  marsh.  It  also  forms  the  ledge  on  which  the 
spindle  buoy  is  set  at  the  entrance  to  Plum  island  sound  from  Ipswich 
bay,  and  the  spindle  buoy  at  the  entrance  of  Essex  river  is  fastened  to  a 
similar  ledge.  On  either  side  of  the  highway  from  Ipswich  to  Woodbury's 
crossing  in  Essex,  all  the  outcrops  are  hornblende  granite,  and  extend 
easterly  to  Hog  island  and  northeasterly  on  both  sides  of  Castle  river. 
West  of  Black  brook  in  Hamilton  and  Topsfield,  all  the  ledges  are  of  this 
granite,  the  outcrops  also  extending  southeast  of  Vineyard  hill  to  Asbury 
Grove  and  to  the  village  of  Wenham,  where  one  ledge  occurs  in  the  rear  of 
the  town  hall.  Moses'  mountain  in  Essex,  is  a  massive  outcrop  of  the 
hornblende  granite,  rising  to  a  height  of  one  hundred  and  eighty  feet  above 
mean  sea-level.  From  this  elevation  a  ridge  of  granite  extends  northerly, 
a  distance  of  over  three  miles  to  Millstone  hill,  east  of  which  there  is  a 
series  of  steep  ledges  known  as  the  Raccoon  rocks.  (See  Figs.  77,  78.) 
At  Coffin's  beach.  West  Gloucester,  the  hornblende  granite  outcrops  south 
and  east  of  the  "Two  Penny  Loaf,"  and  at  several  places  in  the  tidal- 
marsh  and  in  sand-dunes  south  of  the  beach.     (See  Fig.  79.) 

Micrographic  Granite  or  Granophyre.  ^  In  a  contact  surrounding  the 
granite  areas,  and  forming  a  zone  between  the  granite  and  the  augite 
syenite  and  the  diorite  areas,  is  a  micrographic  granite  which  invariably 
cuts  the  diorite  and  augite  syenite  by  long  tongue-ltke  and  dome-shaped 
masses.  It  becomes  an  aplite  dike  granite  at  contacts  with  diorite.  At 
contacts  between  the  augite  syenite  and  granite  it  is  merely  a  fine-grained 
or  micrographic  granite.     It  should  be  considered  as  a  contact-zone  and 


Fig.   79.  — HORNBLENDE    GRANITE    OUTCROPS    BETWEEN    WHICH    A    BASIC    DIKE    ROCK 

HAS    BEEN    REMOVED    BY    DISINTEGRATION. 

South  from   Coffin's  beach,    West  Gloucester. 


Fig.  80.— HORNBLENDE    GRANITE    BOULDER,    AT    ESSEX. 
32  feet  high,    25  feet  wide,   40  feet   long;   estimated   weight,    3,763   tons. 


MICROGRAPHIC    GRANITE    OR    GRANOPHYRE  157 

not  as  a  distinct  rock  formation.  When  studied  from  thin  sections  under 
the  microscope  in  polarized  Kght,  it  is  seen  to  be  different  in  structure 
from  any  variety  previously  described.  The  minerals  are  largely  micro- 
cline,  microperthite,  orthoclase  and  albite.  These  are,  by  the  addition  of 
quartz  grains,  again  broken  up  into  micropegmatite,  forming  a  beautiful 
mosaic.  Other  minerals  are  augite,  titanite,  hornblende,  biotite,  hex- 
agonal sections  of  apatite,  numerous  zircons,  some  colorless  garnets,  and 
magnetite.  In  some  of  the  sections  there  are  fine  masses  of  glaucophane, 
a  probable  decomposition  product  of  hornblende.  One  section  has  micro- 
■cliths  of  segirine  in  the  orthoclase  and  larger  quartz  grains.  The  specific 
gravity  of  the  feldspars  in  the  crushed  rocks,  when  passed  through  the 
90  mesh  sieve  and  separated  in  the  Thoulet  solution,  as  determined  by 
the  Westphal  balance,  gives  2.65  for  the  quartz  and  some  albite,  2.57  for 
the  microcline  and  orthoclase,  and  heavier  minerals  range  between  3 . 2  for 
augite,  and  4.4  for  zircon. 

Occupying  the  region  between  Fresh  Water  Cove  village  and  the  West 
•Gloucester  railroad  station,  and  extending  in  a  southwesterly  direction 
across  Magnolia,  Manchester,  and  to  the  Beverly  shore,  is  an  outcrop  of 
granophyre.  Towards  the  north  this  formation  cuts  the  hornblende 
granite  and  augite  syenite  from  Eastern  point  to  the  shore-line  at  Bass 
Rocks.  From  Rocky  Neck,  East  Gloucester,  to  Bass  Rocks,  the  contact 
•of  this  granophyre  and  the  hornblende  granite  is  strongly  marked  and 
easily  followed.  Across  Little  Good  Harbor  beach  and  opposite  Salt 
island,  to  the  inner  point  of  Briar  Neck,  there  are  numerous  tongues  of  this 
Tock  intruding  into  the  hornblende  granite,  while  the  main  mass  of  the 
Tock  is  seen  on  the  outer  side  of  Salt  island.  It  reaches  the  mainland  on 
the  shore  in  the  middle  of  Long  beach  where  it  divides,  one  part  following 
the  shore-line  to  Cape  Hedge  and  Emerson's  point,  and  reaching  across 
to  the  west  side  of  Loblolly  cove,  while  the  other  mass  cuts  across  the 
■granite  to  Gap  head  and  Straitsmouth  island,  and  appears  in  numerous 
■outcrops  from  Whale  cove  to  the  town  of  Rockport.  Between  Fresh- 
water Cove  village  and  West  Gloucester,  this  granophyre  has  the  appear- 
-ance  of  a  massive  flow;  and  it  has  a  similar  character  where  it  crosses 
Eastern  point  from  Rocky  Neck  to  Bass  Rocks.  On  Emerson's  point  and 
•Gap  head,  however,  it  is  seen  in  dome-shaped  masses  a  few  feet  in  diameter, 
-clearly  embedded  in  granite  and  also  varying  from  this  to  extensive  erup- 
tive forms.  It  is  probable  that  this  entire  formation  has  a  massive, 
iintrusive,  granitic  structure,  which  has  in  places  widened  out  into  dome 
■shapes,  while  in  others  it  has  become  contracted  into  dike  forms  from  a 


158  MICROGRAPHIC    GRANITE    OR    GRANOPHYRE 

few  inches  to  a  number  of  feet  in  width.  It  is  clear  that  some  of  the 
rounded  masses  are  seen  as  surface  outcrops,  by  the  erosion  of  the  surround- 
ing granite  at  a  comparatively  recent  date. 

The  microscopic  structure  of  this  rock,  as  shoAvn  by  a  selection  from 
the  numerous  thin  sections  from  different  outcrops,  is  as  follows : 

No.  I.  From  Eastern  point,  midway  between  Bass  Rock  and  Brace's  cove  : 
Orthoclase,  quartz,  chlorite,  uralite,  magnetite,  and  numerous  small  grains  of  titanite. 
With  a  high  power  objective  under  crossed  nicols,  the  feldspars  and  quartz  present 
the  appearance  of  a  mosaic.  The  feldspars  are  microperthite  intergrowths  of  albite 
and  orthoclase. 

No.  2.  From  the  outer  side  of  Salt  island:  Micropegmatitic  quartz  and  feldspar 
grains,  the  feldspar  grains  being  tabular  Carlsbad  twins  (always  microperthite), 
augite,  green  hornblende,  some  biotite,  magnetite,  iron  pyrite,  and  large  sections 
of  colorless  garnets  in  the  micropegmatitic  quartz  and  feldspar  areas.  With  high 
power  objectives,  even  the  smallest  feldspar  grains  are  seen  to  be  microperthite. 
There  are,  also,  some  micro-zircons  as  inclusions  in  the  feldspars.  The  entire  sec- 
tion shows  that  the  rock  has  been  subjected  to  great  strain,  for  much  of  the  horn- 
blende and  some  of  the  feldspars  are  crushed  and  broken.  Decomposition  in  the 
hornblende  has  produced  feathery-formed  glaucophane. 

No.  3.  Near  Brace's  cove,  southeast:  Quartz  feldspars,  hornblende,  chlorite, 
glaucophane,  and  limonite.  The  quartz  and  feldspars  are  arranged  as  in  the  other 
slides.  The  orthoclase,  which  is  microperthite,  micropegmatitically  arranged,  has 
inclusions  of  hornblende,  limonite,  and  quartz  grains.  The  evidence  of  great  strain 
and  crushing  force,  sufficient  to  separate  the  quartz  grains  from  the  feldspars,  is 
easily  detected.  In  many  cases  a  rim  of  chlorite  surrounds  each  grain,  while  in 
some  instances  the  limonite  surrounds  the  quartz  and  feldspar  grains,  giving  the 
section  the  appearance  of  a  clastic  rock,  usual  in  all  of  the  granulites. 

Many  micro-sections  of  this  rock  from  various  outcrops  have  been 
studied,  and  the  results  all  point  to  the  conclusion  that  this  extensive 
formation  in  the  Cape  Ann  hornblende  granite  area  has  a  granitic  struc- 
ture, and  has  crystallized  from  the  magma  in  an  aggregate  of  small  grains, 
partially  metamorphosed  by  plastic  deformation  subsequent  to  solidifica- 
tion. 

Thompson's  mountain  in  Cape  Ann  park,  is  an  outcrop  of  hornblende 
granite  swept  bare  of  debris,  which  rises  to  an  elevation  of  two  hundred 
and  twenty  feet  above  sea-level.  Essex  avenue,  about  one  mile  distant, 
is  laid  out  in  a  dip  in  this  granite  which  rises  by  the  side  of  the  road  to  a 
height  of  nearly  one  hundred  feet.  From  Brace's  cove  to  Light  House 
point.  East  Gloucester,  all  of  the  massive  outcrops  are  hornblende  granite. 
Aporhyolite  appears  in  a  series  of  dikes  on  Eastern  point,  and  also  forms 
Halfway  rock,  the  Dry  breakers,  and  Gooseberry  islands.     These  intrud- 


Fig.  81.  — PHOTOMICROGRAPH    OF    ACTINOLITE    IN    A    MASS    OF    FAYALITE. 
Rockport. 


Fig.   82.  — PHOTOMICROGRAPH    OF    BIOTITE    OLIVIN    PERIDOTITE. 
Skug  River,  Andover. 


MICROGRAPHIC    GRANITE    OR    GRANOPHYRE  X&l 

ing  aporhyolite  dikes  cut  the  granite  and  indicate  its  greater  age.  North 
of  the  Oak  Grove  cemetery  in  Gloucester,  in  the  Pomeroy  quarry,  the 
hornblende  granite  appears  in  the  form  of  a  pink  feldspar,  rich  in  well- 
crystallized  minerals  which  occur  in  geode-like  pockets  in  the  massive 
granite.  Along  both  sides  of  Mill  river,  the  outcrops  of  hornblende  granite 
are  very  massive  and  extend  to  the  augite  syenite  rocks,  north  of  Annis- 
quam  village.  South  of  the  canal,  at  Stage  Point  head,  Gloucester,  the 
outcropping  bed-rock  is  hornblende  granite,  and  extends  parallel  with 
the  shore  to  Fresh  Water  cove  and  Magnolia.  From  Emerson's  point, 
Rockport,  to  Milk  island  and  Briar  Neck,  all  of  the  outcrops  of  bed-rock 
are  hornblende  granite.  On  the  shore  opposite  Milk  island  there  is  a 
bed  of  arkose,  a  conglomerate  granite,  reconsolidated  from  an  older  granite 
mass. 

Around  Poole's  hill,  the  outcrops  are  hornblende  granite  and  along  the 
shore  from  Sandy  bay  to  Lanesville,  this  granite  forms  a  fringe  between 
high-  and  low-water  mark. 

In  1880,  Fayalite  was  found  by  the  author  in  this  hornblende  granite 
at  Rockport.  This  rare  mineral  was  first  collected  at  Fayal,  in  the  Azores, 
by  Baron  Humboldt.  It  has  been  found  in  the  granite  of  Mourne  moun- 
tain, Ireland,  and  microscopic  crystals  have  been  discovered  in  lithophase 
occurring  in  rhyolite  rocks  at  the  Yellowstone  Park.  The  specimens  col- 
lected at  Rockport  were  parts  of  a  long  crystalline  mass  found  at  a  depth 
of  sixty  feet  below  the  surface  and  near  the  base  of  a  large  boss  or  vein 
of '  pegmatite.  Here  the  Fayalite  occurred  as  a  lenticular  shell  of  vary- 
ing thickness  from  twelve  to  sixteen  inches  in  diameter  and  of  a  dark 
resinous-green  color.  In  connection  with  this  mineral  were  foimd  masses 
of  an  actinolitic  mineral  of  the  usual  leek-green  color.  (See  Fig.  81.)  A 
chemical  analysis  of  this  Fayalite  made  at  the  Sheffield  Scientific  School, 
New  Haven,  gave  the  following  results : ' 

Si02 30.08 

FeO 68.12 

MnO .72 

H2O .80 


Specific  gravity  4.318. 

Off  the  shore  of  Manchester  is  Kettle  island,  an  outcrop  of  pink  feld- 
spar granite  cut  by  a  series  of  very  basic  basalt  dikes.     Great  Egg  rock 

'  American  Journal  of  Science,  Vol.  XVI. 


162  MICROGRAPHIC    GRANITE    OR    GRANOPHYRE 

is  a  bare  ledge  of  hornblende  granite,  on  the  surface  of  which  are  several 
patches  or  remnants  of  a  sill  dike  of  basalt,  the  upper  parts  eroded  and 
cut  away  by  the  action  of  the  sea.  Graves'  island,  which  recently  has 
been  formed  near  the  Manchester  shore,  is  a  massive  outcrop  of  hornblende 
granite.  Within,  eighty  years  a  cart-road  led  to  this  island  which,  in 
1 90 1,  was  nearly  an  eighth  of  a  mile  from  the  shore  with  a  deep-water 
channel  between. 

The  microscopical  structure  of  an  aplite  vein  or  dike  granite  cutting 
the  hornblende  diorite  at  Castle  hill,  Salem,  is  shown  in  the  following 
sections : 

No.  I.  Quartz  and  orthoclase  in  micrographic  structures,  some  lath-shaped  plagio- 
clase,  probably  anorthite,  with  epidote,  limonite,  and  polysynthic-twinning  in  calcite, 
titanite  and  its  decomposition  product  leucoxine,  and  cubical  iron  pyrite. 

Nos.  2-3.   Same  as  No.  i,  with  some  green  hornblende  and  biotite. 

No.  4.  This  section  is  from  a  contact  with  the  diorite.  Much  titanite  and  pyrite. 
Orthoclase,  plagioclase,  and  quartz,  with  numerous  plates  of  calcite  and  crystals  of 
apatite. 

No.  5.  Aplite  in  contact  with  a  diabase  dike.  Orthoclase,  plagioclase,  Labrador- 
ite,  green  hornblende,  augite,  epidote,  calcite,  and  magnetite,  numerous  apatites, 
finely-twinned  glassy  feldspars  seen  with  numerous  polysynthetic-twinned  plates  of 
calcite,  some  secondary  quartz,  biotite,  and  magnetite  developed  at  the  contact  with 
the  dike-rock. 

An  aplite  vein  cutting  quartz  hornblende  diorite  on  the  shore  below 
Clifton  heights  at  Marblehead  (see  Fig.  84),  is  fine-grained  and  usually  of 
a  light  red  to  gray  color,  and  shows  nothing  but  quartz  and  feldspar. 
Under  the  microscope,  in  thin  section,  micrographic  intergrowths  of  feld- 
spar and  quartz  are  seen,  with  a  little  green  hornblende,  brown  biotite  and 
somfe  titanite  and  magnetite. 

The  ledges  in  the  area  between  Cherry  hill,  North  Beverly,  and  FoUy 
hill,  in  Danvers  and  including  the  same,  are  hornblende  granite.  Ex- 
tending from  Beverly  Farms  to  Prides  Crossing  there  is  a  ridge  of  this 
granite  about  one  mile  in  width  with  continuous  outcrops.  Snake  hill 
at  Montserrat,  is  also  hornblende  granite.  Other  outcrops  occur  in  Beverly 
on  Railroad  avenue,  Broadway,  Prospect  hill,  and  Goat  hill  at  the  mouth 
of  Bass  river.  On  Marblehead  Neck,  the  granite  from  Tinker's  island  is 
found  by  the  shore  where  it  cuts  the  slates,  sandstones,  and  quartzites. 
It  also  extends  across  the  harbor  and  makes  its  appearance  about  an  eighth 
of  a  mile  northeast  of  the  causeway,  and  also  cuts  the  diorites  near  the 
railroad  station. 


Fig.   83.— MUSCOVITE    BIOTITE    GRANITE,    FOLIATED. 
Jones  Quarry,  South    Lawrence. 


-APLITIC    GRANITE    DIKE    CUTTING    QUARTZ    HORNBLENDE    DIORITE,    AT    CLIFTON, 
MARBLEHEAD.     THE  ARROWS   INDICATE  THE   DIKE. 


MICROGRAPHIC    GRANITE    OR    GRANOPHYRE  165 

In  Peabody,  the  west  end  of  Btixton's  hill  is  hornblende  granite,  and 
towards  Proctor's  Crossing  are  three  outcrops.  This  granite  also  appears 
on  Mount  Pleasant  on  the  Jacob  C.  Rogers  estate  and  again  near  Fel- 
ton's  comer.  A  short  distance  away,  in  Danvers,  there  is  an  outcrop  north 
of  the  Peabody  and  Danvers  boundstone.  This  long  tongue  of  granite  is 
intruded  into  the  diorite  area  from  the  mass  south  of  Proctor's  brook  in 
Peabody.  South  of  this  brook,  across  the  town  of  Peabody  to  Indian 
hill,  Wyoma,  in  Lynn,  all  the  outcrops  are  of  this  granite  and  cover  an 
area  nearly  four  miles  east  and  west,  and  three  miles  north  and  south. 

The  microscopic  structure  of  thin  sections  taken  from  Davis  Brothers'  quarry 
near  "Ship  rock"  in  Peabody,  is  as  follows:  much  quartz  in  large  xenomorphic 
areas,  some  orthoclase,  much  plagioclase  well  twinned,  probably  Labradorite,  much 
magnetite  and  limonite.  A  number  of  the  thin  sections  show  that  the  rock  has 
been  subjected  to  great  mechanical  strain,  for  all  of  the  multiple-twinned  feldspars 
and  the  quartz  areas  are  cracked,  broken,  and  faulted,  a  serious  defect  in  the  rock, 
permitting  the  minerals  to  separate  and  the  whole  rock-mass  to  crumble.  This  is 
so  pronounced  that  it  is  nearly  impossible  to  make  a  good  thin  section  for  micro- 
scopical study.  There  is  much  chlorite  developed  from  the  decomposition  of  the 
hornblende,  which  gives  the  rock  its  green  color. 

Mountain  street,  Lynn,  is  laid  out  over  a  large  outcrop  of  hornblende 
granite,  and  all  the  outcrops  extending  from  this  point  to  Dread  ledge, 
Swampscott,  and  to  Phillips  beach,  are  of  the  same  granite. 

The  microscopical  structure  is  as  follows:  quartz  in  large  irregular  crystalline 
forms,  with  well  twinned  albite  in  excess  of  orthoclase.  Some  of  the  orthoclase 
crystals  are  microperthitic  intergrowths  of  albite,  one  section  of  inicrocline  showing 
the  basal  cleavage.  Numerous  aggregates  of  brown  hornblende  and  biotite,  some 
augite  surrounded  by  hornblende  and  magnetite,  a  few  zircons,  chlorite,  and  uralite. 
Some  of  the  microperthite  areas  are  micrographic.  Cubical  iron  pyrite  crystals 
appear  in  the  hornblende  and  biotite  areas.  Quartz  is  in  excess  of  all  the  other 
minerals  and  shows  incipient  cracks  and  in  some  areas  is  crushed  and  broken,  the 
cracks  being  filled  with  secondary  silica  or  chalcedony.  Zonal  structure  is  well 
developed  in  some  of  the  orthoclase,  and  in  one  of  the  feldspars  there  is  a  red  garnet 
crystal.     AUanite  and  epidote  are  also  seen  in  some  sections. 

Dolphin  rock,  the  Great  and  Little  Pig  rocks.  Ram  island,  and  Tinker's 
island,  are  outcrops  of  the  same  formation.  A  narrow  ridge  outcrops  at 
Clifton  and  at  Devereux,  with  diorite  and  granophyric  granite  on  both 
sides.  From  Tinker's  island  the  granite  extends  to  the  shore  of  Marble- 
head  Neck  where  it  cuts  slate,  sandstone,  and  quartzite,  and  in  turn  is 
cut  by  veins  of  quartz,  porphyry,  and  porphyritic  diabase.     In  Lynnfield, 


166  PORPHYRITIC    GRANITE 

South  Lynnfield,  and  Peabody,  all  of  the  outcrops  south  of  the  Lowell 
branch  railroad  tracks  are  hornblende  granite.  North  of  Main  street,  in 
Saugus,  the  outcrops  are  granite.  Near  the  school-house  on  this  street, 
the  outcropping  ledge  in  the  form  of  a  ridge  is  granite,  which  extends  to 
the  Saugus  poor-farm.  On  Denver  street,  Saugus  Centre,  the  granite  has 
a  contact  with  aporhyolite  which  outcrops  on  both  sides  of  the  granite 
mass.  In  a  quarry  near  the  railroad  track  on  Denver  street,  specimens 
may  be  obtained,  showing  numerous  forms  from  aporhyolite  trap  and  red 
granite  to  a  simple  fused  granite.  South  and  southwest  of  this  contact 
there  are  three  outcrops  of  a  red  aporhyolite  on  Essex  street,  and  four 
outcrops  at  Cliftondale,  extending  by  other  outcrops  to  the  tidal  marsh  at 
East  Saugus  and  northerly  across  Saugus  Centre  to  Vinegar  hill. 

Porphyritic.  Granite.  —  This  formation  occurs  in  Newburyport,  West 
Newbury,  and  Amesbury.  It  is  much  like  the  hornblende  granite,  but 
contains  numerous  large  porphyritic  crystals  of  microcline.  The  whole 
area  has  been  subjected  to  great  strain  by  a  down-throw  fault  in  the  Parker 
river  valley  between  Georgetown  and  West  Newbury.  This  strain  is  seen 
in  the  large  porphyritic  crystals,  nearly  all  of  which  are  cracked,  bent,  or 
broken. 

Extending  along  the  bank  of  the  Merrimac,  from  the  Artichoke  river 
to  "The  Laurels,"  are  outcrops  of  coarse  porphyritic  granite.  Six  out- 
crops also  appear  at  the  south  and  southwest  in  West  Newbury  extending 
nearly  to  the  base  of  Indian  hill,  and  veins  and  tongues  of  granite  extend 
to  the  Byfield  railroad  station.  Less  than  one  half  of  a  mile  from  the 
outcrops  near  Indian  hill,  the  ordinary  hornblende  granite  appears.  A 
fine-grained  aplitic  dike  granite  also  extends  from  a  point  east  of  Central 
street  in  Byfield,  nearly  to  the  Chipman  silver  mine.  It  is  therefore  evi- 
dent that  the  principal  mass  of  this  granite  lies  at  the  northward,  the 
magma  flowing  southward  and  cutting  the  slates  and  sandstones  of  West 
Newbury  and  the  diorites  of  Newburyport  and  Newbury. 

This  porphyritic  granite  is  also  foimd  north  of  Monday  hill,  in  Ames- 
bury,  and  southeast  of  Grape  hill,  between  Amesbury  and  Salisbury. 
There  are  numerous  outcrops  east  of  Powow  hill,  north  of  Clark's  pond, 
and  extending  to  the  brook  on  the  east  side  of  Black  river,  some  of  which 
are  foHated  in  form.  On  the  Davis  farm,  near  the  Chain  bridge,  an  out- 
crop appears  that  is  slightly  porphyritic.  The  feldspar  phenocrysts  in 
the  outcrops  at  "The  Laurels"  are  sometimes  six  inches  long,  but  usually 
cracked  and  broken,  with  hornblende  mica  and  quartz  filling  the  cracks. 
The  feldspar  phenocrysts  are  microcline. 


PORPHYRITIC    GRANITE  167 

Specimens  of  porphyritic  granite  from  "The  Laurels,"  from  Amesbury, 
and  from  beside  High  street,  near  the  Artichoke  river,  show  the  following 
microscopic  structure : 

Much  quartz,  orthoclase,  and  albite,  parts  of  which  are  perfectly  fresh,  but  all 
more  or  less  crushed  and  broken.  The  cracks  in  the  feldspars  are  filled  with  sec- 
ondary quartz,  calcite,  and  muscovite,  and  there  are  also  some  large  areas  of  crys- 
talline calcite.  Much  chlorite,  some  magnetite,  large  patches  of  limonite,  a  few 
small  areas  of  hornblende  appear,  also  numerous  zircons.  The  quartz  is  allotrio- 
morphic  —  the  quartz  of  typical  granite.  The  extinction  angle  on  the  base  of 
one  of  these  crystals  was  12°  on  the  second  cleavage. 

Numerous  apatite  crystals  are  seen  in  the  chlorite  and  large  pheno- 
crysts  of  microcline  microperthite,  some  of  which  are  five  inches  long, 
and  one  and  one  half  inches  broad,  are  scattered  through  the  rock-mass. 
They  are  usually  bent,  broken,  and  partially  crushed. 

In  Amesbury,  part  of  the  area  of  this  granite  is  gneissic.  The  foHa- 
tion  is  north  and  south ;  the  dip  east.  In  this  gneiss  the  large  pheno- 
crysts  are  filled  with  inclusions  of  quartz  and  albite.  East  of  Powow  hill, 
the  outcrops  show  the  following  microscopical  structure : 

Orthoclase,  albite,  quartz,  and  hornblende,  with  muscovite  and  biotite.  The 
large  phenocrysts  of  feldspar  are  as  in  the  other  sections,  but  show  more  distortion 
and  crushing.  The  cracks  are  filled  with  muscovite  and  quartz  and  the  general 
mass  of  the  quartz  seems  to  be  hypidiomorphic.  Numerous  fluid  inclusions  are 
seen  in  the  quartz.  The  hornblende  is  very  weak,  being  largely  decomposed  to 
limonite  and  calcite.  There  is  much  titanite  and  its  decomposition  product  leucox- 
ene,  also  considerable  chlorite.  Zircons  with  extinction  parallel  to  the  prism  and 
pyramid  are  abundant.  Some  secondary  glassy  albite  feldspars  are  scattered 
through  the  section ;  the  original  feldspars  being  crushed  and  faulted,  and  the  cracks 
filled  with  quartz,  muscovite,  and  calcite.  The  quartz  and  muscovite  are  plainly 
secondary  minerals  due  to  metamorphism  of  the  feldspars.  In  some  of  the  areas 
which  show  this  crushing,  all  of  the  albite  crystals  are  filled  with  glassy  microliths. 


CHAPTER  VI 

MUSCOVITE  BIOTITE  GRANITE 

In  the  northern  part  of  the  County,  and  occupying  nearly  the  whole 
region  of  Andover,  West  Andover,  South  Lawrence,  a  large  part  of  North 
Andover,  Bradford,  Ayer's  Village  in  Haverhill,  and  extending  into  New 
Hampshire,  the  bed-rock  is  muscovite  biotite  granite  passing  into  a  foli- 
ated form.  In  Andover  and  North  Andover,  the  strike  is  east  40°  north, 
parallel  to  the  metamorphic  slate. 

On  the  east  side  of  the  Shawsheen  river,  the  bed-rock  outcrops  which 
skirt  the  base  of  Carmel  hill  are  a  coarse  muscovite  mica-granite.  There 
are  other  outcrops  of  this  granitic  gneiss  at  Pine  hill  and  on  Highland  and 
Summer  streets.  From  the  Andover  Theological  Seminary  to  Foster's 
pond,  and  also  on  both  sides  of  Skug  river,  there  are  occasional  outcrops 
scattered  over  the  area.  In  several  old  quarries,  both  a  fine-  and  coarse- 
grained mica-granite  is  found.  On  Lowell  street,  south  of  Hackett's 
pond,  there  are  five  outcrops,  and  east  of  Skug  river  there  is  a  massive 
outcrop  of  nearly  bare  rock  having  an  elevation  of  280  feet.  These  out- 
crops extend  to  Swan  pond  in  North  Reading,  to  Forest  pond  in  Middle- 
ton,  and  as  far  west  as  Boston  brook.  West  from  Ingalls'  Crossing  station 
there  are  five  outcrops  beside  the  Middleton  and  Andover  turnpike. 

West  of  the  Andover  poor-farm  there  is  a  large  outcrop  of  this  coarse 
granite,  and  Den  rock,  in  North  Andover,  is  of  the  same  formation.  An 
outcrop  at  Machine  Shop  village,  in  North  Andover,  is  cut  by  a  vein  or 
dike  of  aplitic  granite.  Across  Cochichewick  brook,  at  the  western  base  of 
Osgood's  hill,  are  three  outcrops,  and  an  exposure  occurs  by  the  roadside 
near  Tyler's  hill  in  Andover. 

Muscovite  Biotite  Granite,  Foliated.  —  This  white  gneiss  occurs  in  a 
broad,  irregular  belt,  having  its  greatest  development  in  Andover  where  it 
occupies  the  greater  part  of  the  area  of  the  town  and  extends  southward 
into  Middlesex  County.  At  Ballardvale,  it  occtirs  in  massive  formation. 
The  best  exposures  are  at  the  W.  J.  Jones  quarries  in  South  Lawrence, 
where  it  is  worked  for  foundation  stones  (see  Figs.  83,  85,  86).  Here  the 
coarse  gabbro  and  basalt  dikes  and  sills  are  intruded  into  the  mica-granite 

168 


-GRANITIC    WHITE    GNEISS    ARKOSE. 
Jones   Quarfy    West  Andover. 


-GRANITIC    WHITE  GNEISS,    WITH    MUCH    MUSCOVITE. 
Jones   Quarry,  South    Lawrence, 


MUSCOVITE    BIOTITE    GRANITE,    FOLIATED  171 

and  probably  have  metamorphosed  the  rock-mass.  Garnets  are  abundant. 
They  are  always  of  secondary  origin  in  igneous  rocks  and  are  due  to  meta- 
morphism. 

This  white  gneiss,  with  its  pegmatite  masses  and  veins  cutting  the 
bedded  mica-schists  and  sandstones,  is  without  doubt  an  igneous  erup- 
tive rock-mass.  Crushing  may  be  seen  in  this  quarry,  producing  a  granite 
arkose.  The  strike  at  this  point  is  east  20°  north ;  dip  85°  south  of  west. 
The  microscopic  structure  of  sections  of  this  rock  is:  coarse  masses  of 
orthoclase,  microcline,  quartz,  muscovite,  and  garnets,  cemented  together 
by  a  thin  fikn  of  secondary  quartz.  Numerous  inclusions  of  quartz,  bio- 
tite,  and  muscovite,  occur  in  the  feldspars.  Long  tongues  of  this  gneiss 
extend  north  and  northeast,  cutting  the  bedded  mica-schists  at  Salem, 
N.  H.,  and  in  the  northwestern  part  of  Haverhill.  At  Ayer's  Village,  the 
rock  is  a  coarse-  to  fine-grained  biotite  gneiss,  the  color  varying  from  white 
or  light-gray  to  dark-gray.  At  North  Andover  it  is  quite  massive  without 
distinct  foliation,  while  at  West  Andover  and  South  Lawrence  it  is  well 
foliated  and  of  a  imiform  color.  The  narrow  belt  that  runs  into  the  bedded 
mica-schists,  slates,  and  sandstones  of  Lawrence,  Metheun,  and  Haverhill, 
shows  lines  of  contact  in  various  places.  Some  of  these  contacts  cut 
across  the  strike  of  bedded  mica-schists  and  sandstones,  and  it  is  seldom 
that  an  outcrop  does  not  contain  veins  of  granitic  gneiss  cutting  through 
the  schist.  North  of  Ayer's  Village  this  gneiss  cuts  the  schists  parallel  to 
their  bedding-planes  and  sheets  of  schist  torn  from  the  principal  mass 
are  seen  projecting  into  the  granitic  gneiss.  Here  is  the  most  striking 
proof  of  the  eruptive  character  of  the  granitic  gneiss.  These  inclusions  of 
schist,  in  the  granitic  white  gneiss,  vary  in  size  from  a  few  inches  to  many 
feet  in  length,  and  may  be  linear  or  very  irregular  in  form.  A  large  inclu- 
sion of  a  biotite-schist  occurs  on  Main  street,  Andover,  south  of  Carmel 
hill,  and  contains  hornblende,  which  is  almost  wholly  wanting  in  the  gra- 
nitic white  gneiss.  Rounded  and  irregular  bosses  of  hornblende  diorite 
also  occur  in  the  gneiss. 

The  presence  of  numerous  pegmatite  dikes  in  this  granitic  gneiss  also 
indicate  its  eruptive  origin.  These  dikes,  or  masses,  cross  and  also  run 
parallel  to  the  foliation  of  the  granitic  gneiss.  The  contact  is  never  sharp, 
and  they  frequently  merge  into  the  gneiss,  both  containing  the  same  min- 
erals. Garnets  are  abundant  in  the  gneiss  and  pegmatite  in  the  Andover 
area. 

The  ordinary  form  of  the  granitic  gneiss  is  a  light-colored  and  rather 
fine-grained  rock.     The  amount  of  biotite  varies  considerably.     Wherever 


172  MUSCOVITE    BIOTITE    GRANITE,    FOLIATED 

it  is  most  abundant,  the  rock  is  a  light-gray,  well  foliated  gneiss;  where 
least  abundant  it  is  nearly  white  and  of  a  granitic  appearance.  In  some 
localities  in  North  Andover  it  becomes  perfectly  massive.  An  excellent 
example  may  be  found  near  the  Marble  Ridge  railroad  station.  The 
strike  of  the  main  body  of  this  gneiss  is  north  20°  east,  and  the  dip  45° 
west.  Joint-planes  cut  the  gneiss  in  two  or  more  directions,  one  nearly  or 
quite  parallel  to  the  foliation  and  others  at  a  right  angle. 

Microscopically  examined  in  thin  section,  this  rock  is  found  to  be  composed  of  a 
granitic  mixture  of  feldspars,  quartz,  and  plates  of  muscovite,  with  some  biotite. 
Hornblende  is  rare.  One  section  shows  green  hornblende  which  seldom  is  seen 
macroscopically  in  new  exposures  in  the  field.  The  feldspars  usually  present  an 
allotriomorphic  aggregate  of  grains.  Orthoclase  is  most  abundant,  and  an  acid 
plagioclase  is  of  common  occurrence.  Microcline  also  occurs  in  large,  irregular 
grains.  Micrographic  intergrowths  of  orthoclase,  plagioclase,  and  quartz  are  seen, 
the  latter  taking  the  form  of  narrow  irregular  curving  or  angular  inclusions  converg- 
ing towards  the  center  of  the  feldspar  grains.  Titanite  is  present  in  small,  rounded, 
and  lenticular  grains.     Red  garnet  is  the  most  common  accessory  mineral. 

In  an  area  about  a  mile  wide,  on  the  west  side  of  Crystal  lake  (Creek 
pond)  in  Haverhill,  the  granite  gneiss  shows  granulitic  facies  towards 
the  contact  with  the  mica-schist.  South  of  the  lake  occurs  the  ordinary 
granitic  gneiss  merging  into  the  muscovite  biotite  granite.  The  width  of 
the  granulite  border  varies  from  one  or  two  feet  to  many  yards.  Where 
typically  developed,  it  is  a  fine-grained,  light-gray  rock,  and  sometimes  is 
pure  white.  At  the  contact,  red  garnets  are  abundant.  When  micro- 
scopically examined  in  thin  sections  it  is  found  to  be  composed  of  a  fine- 
grained aggregate  of  orthoclase,  plagioclase,  microcline,  quartz,  and  mus- 
covite, with  garnets,  limonite,  some  biotite,  and  iron  pyrite.  At  several 
localities  the  granulite  can  be  followed  from  the  contact,  and  is  seen  to 
pass  gradually  into  the  ordinary  granitic  gneiss.  The  rock  at  first  becomes 
coarser,  loses  its  granulitic  structure  and  assumes  the  granitic  form.  The 
garnets  disappear  and  biotite  becomes  abundant,  together  with  magnetite 
and  limonite.  Bands  of  the  granulite  occur  cutting  across  the  bedded 
slate.  Often  they  are  less  than  an  inch  in  thickness,  but  connect  with  the 
main  mass  of  the  rock.  Some  of  these  small  bands  contain  much  musco- 
vite and  are  well  foliated.  The  intrusive,  eruptive  nature  of  the  granulite 
is  thus  made  apparent. 

From  Tewksbury,  extending  easterly  along  the  southern  bank  of  the 
Merrimac  river  for  nearly  a  mile,  there  is  a  continuous  outcrop  of  coarse 
mica-granite,  in  part  gneissic,  cutting  slate  that  is  greatly  metamorphosed, 


MUSCOVITE    BIOTITE    GRANITE,    FOLIATED  173 

it  now  being  a  very  hard,  tough  rock.  The  granite  penetrates  the  slate 
parallel  to  its  bedding,  the  strike  being  northeast  to  southwest  and  the  dip 
40°  northwest.  These  steep  rocks  are  locally  known  as  "  Deer  Leap  rocks," 
they  being  on  a  noted  runway  for  deer  in  colonial  times.  North  of  these 
rocks  there  is  an  outcrop  of  quartz  mica  diorite.  The  exact  contact  is 
concealed  by  drift-sand  and  river  silts.  In  the  bed  of  a  brook,  near  the 
boundary  between  Tewksbury  and  Andover,  there  is  an  outcrop  of  this 
gneiss  having  the  same  formation  as  that  found  at  the  Jones  quarry  in 
West  Andover.  From  the  strike  of  the  outcrops  it  may  be  presumed  that 
the  bed-rock  for  this  entire  area  is  mica-granite,  in  some  places  becoming 
a  granitic  gneiss. 

Southwest  of  Fish  brook  in  Andover,  on  both  sides  of  the  river  road, 
there  are  outcrops  of  a  diabasic  diorite,  and  other  outcrops  are  to  be  seen 
on  the  westerly  side  of  Wood  hill  extending  nearly  to  "Deer  Leap  rocks." 
The  Wood  hill  outcrop  is  an  augite  hornblende  gabbro.  This  gabbro  is 
identical  in  structure  with  the  rock  at  the  Dracut  nickel  mine.'  Recent 
excavations  for  sewer  pipes  reveal  this  rock  in  South  Lawrence,  and  it  is 
probable  that  dikes  and  sills  of  this  gabbro  erupted  into  the  foliated  granite, 
produced  the  crushed  arkose  in  the  bottom  of  the  Jones  quarry  at  West 
Andover.  Little  or  no  tilting  from  the  original  foliation  is  seen  in  this 
quarry.  The  foliation  is  perfectly  fiat  and  horizontal  until  a  depth  of  ten 
feet  is  reached,  below  which  the  rock  is  shattered  and  reconsolidated  into 
a  typical  arkose,  in  which  there  are  zones  of  a  very  fine  basic  slaty  rock. 
The  individual  grains  in  these  zones,  when  studied  from  thin  sections  with 
the  microscope,  appear  to  be  parts  of  a  crushed  rock  and  not  the  usual 
roimded  sedimentary  water-worn  grains.  Probably  at  a  greater  depth  than 
any  excavation  that  has  yet  been  made,  some  dike  in  the  form  of  a  sill  has 
been  forced  through  the  gneissic  granite  parallel  to  its  foliation  and  pro- 
duced this  crushed  formation. 

Between  Bear  hill  and  Lake  Cochichewick,  there  are  several  outcrops 
of  this  granite  about  one  fourth  of  a  mile  wide,  extending  into  Boxford 
in  a  northeasterly  course  for  about  a  mile.  Outcrops  also  occur  near 
Johnson's  pond,  in  South  Groveland.  On  widening  the  road  opposite 
Lake  Saltonstall,  in  Haverhill,  a  mass  of  granitic  gneiss  was  uncovered 
for  a  length  of  over  two  hundred  yards.  It  is  probably  a  vein  or  dike  of 
the  mica-granite  which  is  massive  at  the  north,  in  Salem  and  Atkinson,  N.  H. 

Paisanite,  a  granite  porphyry  dike  rock  with  granophyric  and  micro- 

'  This  ore  contains  only  .0023  of  one  part  of  nickel. 


174  PAISANITE 

pegmatitic  tendencies,  occurs  below  high  tide  in  the  small  bay  between 
Woodbury's  point  and  Hospital  point  at  Beverly.  The  trend  is  north  25° 
east.  This  outcrop,  which  was  discovered  in  1888,  is  about  forty  feet 
long  and  ten  feet  wide  and  is  exposed  at  low  water.  The  microscopical 
structure  is  as  follows : 

Quartz  of  two  generations,  a  granular  mass  and  also  pyramids  of  quartz  pheno- 
crysts,  is  thickly  scattered  through  the  dark-gray  ground-mass,  together  with  pheno- 
crysts  of  white  feldspars.  The  feldspars  are  stout  prisms.  Hornblende  and  biotite, 
the  former  in  microliths,  are  very  abundant  and  pleochroic  to  a  high  degree  from 
blue  to  yellow.  Glaucophane  crystals  are  also  seen.  The  feldspars  are  microperthite 
and  are  filled  with  dust-like  inclusions. 


Fig,  87.  — QUARTZ    AUGITE    SYENITE. 
Poorhouse   Hill,  Beverly. 


Fig.  88.— AUGITE    SYENITE. 
Dudley  L.  Pickman  estate,  Beverly  Co 


CHAPTER  VII 

THE    SYENITE    ROCKS 

The  syenite  rocks  of  Essex  County  are  igneous  eruptives,  and  intru- 
sives,  in  dike  forms,  the  principal  mass  being  of  the  granitic  type.  Many  of 
the  outcrops  are  very  distinctive  in  form  and  of  different  textures  and 
colors,  due,  in  part,  to  the  basic  minerals  in  their  composition.  In  the 
present  work  these  rocks  are  divided  into  several  distinct  series. 

Essexite,  the  type  of  one  series  of  basic  syenites,  is  the  oldest  form. 

Salemite,  a  foliated  basic  type  containing  nepheline  and  augite. 

Nepheline  syenite,  an  acid  rock  containing  nepheline. 

Quartz  augite  syenite,  or  akerite,  having  no  nepheline. 

Pulaskite,  having  little  or  no  nepheline. 

Arfvedsonite  mica  syenite. 

.42girine  syenite. 

Hedrumite,  having  neither  nepheline  nor  hornblende. 

Nordmarkite,  a  mica  hornblende  quartz  syenite. 

Solvsbergite,  or  Bostonite  porphyry,  a  dike  rock. 

Biotite  tinguaite,  a  dike  rock. 

^girine,  or  analcite  tinguaite,  a  dike  rock. 

Camptonite,  a  dike  rock. 

Kersantite,  a  dike  rock. 

Umptekite,  or  hornblende  gabbro,  a  massive  basic  rock  associated  with 
the  syenites. 

Keratophyre,  a  lava  flow  covering  the  aporhyolites  on  Marblehead 
Neck. 

These  types  are  subdivided  into  various  forms.  Essexite,  for  ex- 
ample, is  a  massive,  slightly  porphyritic  rock  nearly  black  in  color,  which 
contains  nepheline  without  olivin.  There  is  also  a  micaceous  Essexite, 
having  biotite  in  excess  in  the  form  of  a  ferro-magnesian  mineral.  Thirdly, 
an  Essexite  of  a  light-blue  color,  having  little  or  no  nepheline,  and  lastly, 
a  foliated  Essexite  of  light-blue  color,  having  much  nepheline.  Umpte- 
kite, or  hornblende  gabbro,  is  a  series  in  which  the  umptekite  variety  of 
hornblende  is  sometimes  seen  in  large  cleavable  masses.     Sometime,s  it  is 

177 


178  THE    SYENITES    OF    SALEM    NECK 

fotuid  to  be  a  mica  hornblende  gabbro  with  an  excess  of  biotite  over  horn- 
blende. In  the  larger  part  of  the  area  where  it  occurs  it  shows  about 
equal  amounts  of  hornblende  biotite  and  feldspar.  This  is  the  hornblende 
gabbro  type  of  Professor  Washington,  found  on  Salem  Neck.  In  connection 
with  the  dike  rocks  already  enumerated  there  are  at  least  twenty  as  yet 
undetermraed  which  are  probably  members  or  apophyses  of  the  main 
syenite  mass. 

An  outcrop  of  akerite  appears  at  Lynnfield,  in  the  southwestern  part 
of  the  CoTinty,  in  an  old  abandoned  railroad  quarry,  south  from  Filling's 
pond.  An  intrusive  in  the  hornblende  granite,  without  doubt  it  is  a  tongue 
extending  from  North  Reading,  where  it  is  the  principal  rock  of  the  region. 
From  Lynnfield  this  tongue  extends  southeasterly  to  Wyoma  lake  in 
Lynn.  Branches  also  reach  into  the  hornblende  granites  of  Peabody. 
This  formation  is  augite  syenite  or  akerite  of  Professor  Washington.  There 
are  two  forms:  a  quartz  augite  syenite  (see  Fig.  87),  and  a  form  without 
quartz,  though  sometimes  it  is  microscopically  present  as  intersertial  blebs 
between  feldspars.  The  quartz  augite  syenite  outcrops  along  the  shore 
between  Beverly  Cove  and  Gale's  point,  Manchester,  in  connection  with 
hornblende  granite  and  dike  rocks.  In  a  quarry  on  the  estate  of  W.  D. 
Pickman,  at  Beverly  Cove,  the  typical  augite  syenite  is  found  with  little 
or  no  quartz.  (See  Fig.  88.)  Other  exposures  are  seen  near  the  railroad 
station  in  Essex  and  also  at  Conomo  point.  East  of  the  Magnolia  railroad 
station  the  first  ledge  is  augite  syenite.  Another  outcrop  may  be  seen 
near  the  poor-farm  at  Gloucester.  These  syenites  occur  in  an  area  eight 
miles  wide  and  twelve  miles  long,  including  the  territory  occupied  by 
Marblehead,  Salem,  Beverly,  Hamilton,  Wenham,  Essex,  and  Manchester. 
Another  area  occurs  in  Gloucester  and  Rockport  and  although  not  so  great 
as  the  last,  it  contains  a  larger  number  of  outcrops. 

The  Syenites  of  Salem  Neck  and  Vicinity.  —  The  oldest  rocks  in  the 
area  comprising  Salem  Neck,  Winter  island,  and  vicinity,  are  the  sedi- 
mentary beds  of  slate  and  sandstone,  both  remnants  of  a  series  of  Cambrian 
sediments.  Next  in  order  is  the  hornblende  diorite,  which  is  seen  cutting 
these  Cambrian  rocks.  Then  follow  the  rocks  of  the  syenite  group  in 
turn  cutting  and  brecciating  the  diorite.^  These  syenites  were  erupted 
from  beneath  the  older  diorites,  cracking  them,  and  filling  the  openings 
with  the  syenite  magma.     (See  Figs.  89,  90.) 

'  The  author  has  plotted  all  the  outcrops  of  bed-rock  in  this  area,  described  in  the 
following  pages,  upon  a  map  drawn  to  a  scale  of  300  feet  =  one  inch,  and  contemplates  its 
early  publication  together  with  a  paper  on  the  geology  of  the  locality. 


Fig.  89— BRECCIATED    HORNBLENDE    DIORITE    CUT    BY    VEINS    OF    PULASKITE    SYENITE. 
Near  Beverly  Bridge,  Salem. 


Fig.  90.  — HORNBLENDE    DIORITE    CUT    BY    VEINS    OF    PULASKITE    SYENITE    AND    DIABASE. 
Near   Beverly  Bridge,  Salerr. 


THE    SYENITES    OP    SALEM    NECK  181 

At  the  contact  of  the  pulaskite  and  diorite,  there  is  a  slight  metamorph- 
ism  of  the  minerals ;  the  plates  of  biotite  in  the  diorite  are  larger  and  more 
frequent,  and  greater  masses  of  hornblende  have  been  developed  in  the 
pulaskite  than  elsewhere.  The  remnants  of  the  sedimentary  rocks  on 
Winter  island  and  across  the  harbor  on  Naugus  Head,  are  deeply  meta- 
morphosed from  sandstones  into  a  hard,  compact  quartzite.  The  slates 
have  been  transformed  into  mica-schists,  and  the  limestones  into  chert,  by 
the  intrusion  of  diorites,  syenites,  and  dike  rocks. ^ 

On  Bentley's  hill  there  is  a  dike  in  the  form  of  a  vein  of  pegmatite. 
Nepheline  occurs  in  large,  irregular  masses,  also  hydronephelinite,  and 
some  radiated  nepheline.  Sodalite  is  also  present  in  large,  irregular  blue 
patches,  and  zircon  crystals,  from  3  to  7  mni.  in  length,  are  not  uncommon. 
East  from  this  nepheline  syenite  outcrop,  there  is  a  wide  exposure  of  horn- 
blende gabbro  which  extends  to  the  road.  Across  the  road  are  outcrops 
of  Essexite  with  little  or  no  nepheline,  and  upon  the  hill  is  an  outcrop  of 
very  coarse  mica  syenite,  without  nepheline,  which  cuts  the  hornblende 
gabbro. 

There  are  exposures  of  Essexite  on  the  shore  of  Collins'  cove,  south- 
west of  the  poorhouse,  and  eighteen  different  outcrops  may  be  counted 
beside  Fort  avenue.  From  Fort  Lee,  for  a  distance  of  fifteen  hundred 
yards,  the  outcrops  are  pulaskite  syenite  and  hornblende  gabbro.  For 
the  remainder  of  the  distance  to  the  wharf  at  the  Willows,  there  are  five 
outcrops  of  Essexite,  hornblende  gabbro,  and  nepheline  syenite.  In  con- 
tact with  the  nepheline  syenite  is  a  mass  of  Essexite,  south  of  which  is  a 
contact  with  hornblende  gabbro.  Proceeding  southerly  along  the  shore, 
the  next  outcrop  is  nepheline  syenite  with  a  hornblende  gabbro  contact. 
The  trend  of  the  outcrops  of  Essexite  between  ColHns'  cove  and  the  wharf 
at  the  Willows,  is  northeast  to  southwest. 

The  hedrumite  form  of  pulaskite  is  first  seen  on  the  north  side  of  the 
poor-farm  wharf  and  is  continuous  by  outcrops  on  the  Beverly  harbor 
side  for  about  fifteen  hundred  yards.  The  orbicular  or  hornblende  syenite 
occupies  a  small  area  on  the  shore,  nine  hundred  yards  northeast  of  the 
poor-farm  wharf. 

The  outcrops  of  bed-rock  on  Winter  island  are  nearly  all  confined  to 
the  shore  at  Cat  cove  and  the  sea-shore  on  the  other  side  of  the  island. 

1  Professor  Brogger  of  Norway,  who  visited  this  locality  May  30,  igoo,  considers  this 
area  of  syenite  rocks  originally  to  have  been  in  the  form  of  a  bathylitic  structure,  and 
that  varying  degrees  of  cooling  and  solidification  of  the  magma  produced  the  various 
groups  or  series  of  sheets,  of  unequal  thickness,  all  chemically  related  to  each  other. 


182  THE    SYENITES    OF    SALEM    NECK 

The  first  outcrop  south  of  the  causeway  is  hornblende  gabbro,  which  ex- 
tends for  one  hundred  yards,  and  is  cut  by  a  porphyritic  diabase  dike 
twenty-five  inches  in  width,  having  a  trend  north  20°  east.  Both  are  cut 
by  pulaskite  syenite  veins.  Continuing  south,  the  next  outcrop  is  horn- 
blende gabbro  cut  by  veins  of  pulaskite,  beyond  which  is  nepheline  syenite 
for  a  distance  of  three  hundred  yards.  At  the  point,  there  is  a  vein  of 
hedrumite,  six  feet  wide,  which  cuts  the  gabbro.  On  the  next  point,  the 
outcrop  is  hornblende  diorite,  which  is  also  found  on  the  Hathome  farm  on 
the  Neck.  Higher  up  on  the  ridge  are  two  outcrops  of  the  hornblende 
gabbro  cut  by  veins  of  pulaskite.  On  the  shore  of  Cat  cove,  fifty  yards 
south  of  the  diorite  outcrop,  there  are  two  exposures  of  pulaskite  syenite ; 
and  one  hundred  and  fifty  feet  farther  south,  there  is  an  outcrop  of  the 
gabbro  rock.  The  next  outcrop  is  diorite,  and  occurs  on  a  small  point- 
These  outcrops  of  diorite  and  gabbro  are  brecciated  by  veins  of  pulaskite 
and  nepheline  syenite,  the  latter  occurring  in  veins  from  one  to  six  inches 
in  width.  The  nepheline  occurs  in  large  blebs  in  the  center  of  the  veins. 
These  outcrops,  as  well  as  the  hornblende  gabbro,  are  cut  by  narrow  veins 
of  pulaskite  syenite.  The  gabbro  extends  to  the  point  near  the  powder- 
house. 

Near  the  powder-house  on  Winter  island  are  exposures  of  Essexite, 
cut  by  pulaskite  veins.  Near-by  a  dike  of  porphyritic  diabase,  eighteen 
inches  in  width,  runs  parallel  with  the  shore ;  and  several  small  basic  dikes 
of  olivin  basalt,  from  one  to  five  inches  in  width,  cut  the  other  members 
of  this  group  of  rocks.  Along  the  shore,  between  the  powder-house  and 
the  lighthouse,  there  is  an  outcrop  of  hornblende  gabbro  two  hundred 
yards  in  length.  A  small  outcrop  of  pulaskite  then  follows,  and  is  suc- 
ceeded by  a  mass  of  diorite  ramified  by  veins  of  gabbro  and  pulaskite. 
This  diorite  extends  to  the  cove  in  front  of  the  light-keeper's  house.  On 
the  shore,  near  the  center  of  the  cove,  there  is  an  outcrop  of  Essexite  and 
seventy  feet  distant,  toward  the  south,  dikes  of  gabbro  and  diorite  are 
exposed,  showing  veins  of  pulaskite.  One  hundred  and  fifty  feet  north  of 
the  lighthouse  are  outcrops  of  Essexite  cut  by  veins  of  pulaskite,  and  be- 
yond is  an  outcrop  of  Cambrian  slate  and  sandstone  metamorphosed  into 
a  mica-schist,  such  as  may  be  foimd  at  Naugus  Head  and  also  on  the 
Marblehead  shore.  This  slate  outcrop  extends  to  the  northeasterly  side 
of  Fort  Pickering.  At  the  last  angle  of  the  fort,  on  the  same  side,  are 
outcrops  of  diorite  cut  by  veins  of  pulaskite,  beyond  which  are  veins  of 
pulaskite  cutting  mica  syenite.  On  the  shore,  in  the  valley  northeast  of 
the  fort,  there  is  an  outcrop  of  orbicular  or  hornblende  syenite,  fifteen 


Fig.  91.  — SALEMITE,    ON    THE    SOUTH    SIDE    OF    FORT    AVENUE,    SALEM    NECK. 


HHI 

^^^ 

» 

1^^ 

^^^ 

tk^^zt 

^^^[^Hf^ 

H 

ii||gl||| 

B^ 

^r            * 

f^^^ 

mjt^'-'-"'^^ 

^h^mI^^V 

^^^^^^V   'l-x 

^3 

bJwflfB^B^^^flS 

Fig.  92.  — ESSEXITE,   CUT    BY    VEINS    OF    PULASKITE    SYENITE    AND   CAMPTONITE,    NORTH    SIDE 
OF    FORT    AVENUE,    SALEM    NECK. 


ESSEXITE  185 

feet  in  width,  in  contact  with  nepheline  syenite  and  a  coarse  mica-schist. 
Towards  the  northeast  the  contact  is  with  hornblende  gabbro.  Three 
hundred  feet  of  beach,  composed  of  drift,  then  intervenes  with  two  small 
outcrops  of  mica  syenite  and  an  outcrop  of  hornblende  gabbro,  ten  feet  in 
width,  and  is  succeeded  by  an  exposure  of  pulaskite,  three  hundred  feet 
wide,  and  another  of  light-blue  foliated  Essexite,  two  thirds  as  wide. 

At  the  point  are  outcrops  of  hornblende  gabbro  and  pulaskite,  and  a 
hundred  feet  beyond  is  Essexite,  which  extends  into  Little  Good  harbor. 
On  the  south  shore  of  Little  Good  harbor  are  exposures  of  nepheline  and 
mica  syenite  extending  to  the  inner  point.  Beyond  is  pulaskite,  followed 
by  other  outcrops  of  nepheline  and  mica  syenite,  which  continue  to  the 
causeway.  On  the  north  side  of  Little  Good  harbor,  all  the  outcrops  are 
hornblende  gabbro  cut  by  numerous  dikes  and  small  veins  of  pulaskite 
syenite,  camptonite,  diabase,  and  olivin  basalt.  A  camptonite  dike  over 
two  feet  wide  cuts  across  Juniper  point  from  the  southwest  to  the  north- 
east. Running  parallel  is  a  large  dike  of  diabase,  in  which  the  large  feld- 
spar crystals  have  become  absorbed  or  eroded  by  the  glassy  ground- 
mass,  and  left  as  round  dots  over  the  surface  of  the  rock.  Southwest 
from  the  Salemite  outcrop  on  Salem  Neck,  all  of  the  ledges  are  hornblende 
diorite,  with  some  small  areas  of  hornblende  gabbro.  Both  are  cut  by 
veins  of  pulaskite  syenite.  This  diorite  is  the  bed-rock  of  the  Hathome 
farm  and  the  "Point  of  Rocks,"  and  continues  westerly  across  Salem. 
Forms  of  the  hornblende  gabbro,  with  areas  of  diorite,  comprise  the  larger 
number  of  the  outcrops  of  bed-rock  on  Winter  island,  Salem  Willows,  and 
the  area  west  of  Fort  Lee.  There  are  also  numerous  dikes  of  diabase, 
olivin  basalt,  camptonite,  and  pulaskite  syenite. 

Essexite.  —  Essexite  is  a  porphyritic  rock  and  resembles  porphyritic  dia- 
base, except  that  it  contains  nepheline.  (See  Fig.  92.)  Its  color  is  almost 
black.  Another  form  of  Essexite  has  a  similar  color,  but  is  not  porphy- 
ritic, and  contains  much  biotite.  Still  another  form  is  light-blue  in  color, 
and  is  fine-grained.  The  rock  seems  to  be  holo-crystalline,  like  a  dike 
rock,  but  in  reality  it  is  a  massive  boss  in  the  nepheline  syenite  area. 

Microscopical  examination  of  thin-sections  of  this  rock  shows  that  it  is  com- 
posed of  augite,  green  and  brown  hornblende,  biotite,  plagioclase,  and  an  abundance 
of  titanite  and  rutile  microliths,  micro-zircons,  and  apatite.  The  porphyritic  plagio- 
clase crystals  and  also  the  hornblende  areas  are  seen  to  have  numerous  patches  of 
eteolite  and  perhaps  sodalite,  as  inclusions  in  them.  The  sodalite  being  isotropic 
and  both  the  minerals  in  the  section,  after  treatment  with  hydrochloric  acid  and 
staining  with  fuchsin  in  water,  show   the  plagioclase  and  hornblende  to  contain 


18G  SALEMITE 

numerous  areas  of  these  minerals  which  gelatinize.  Some  of  the  nepheline  in  these 
sections  contains  numerous  feathery  and  fan-shaped  zeolites  that  are  probably 
natrolite.  These  are  displacements  of  the  decomposing  nepheline.  Everywhere  on 
the  surface  this  decomposition  of  the  nepheline  is  seen  changing  the  color  of  this 
mineral  from  an  oily-green  to  a  dull-lead  color.  The  biotite  is  very  fresh  and  of  a 
red  color.  Granular  masses  of  leucoxene  surround  grains  of  titaniferous  magne- 
tite, secondary  products  from  the  decomposition  of  this  iron  ore.     (See  Fig.  93.) 

Salemite.  —  West  from  the  Essexite  group  on  Salem  Neck  is  a  mass  of 
hornblende  gabbro  about  ten  rods  wide  (see  Figs.  91,  107),  cut  by  nu- 
merous veins  and  dikes  of  pulaskite  syenite  and  basic  dikes  of  camptonite. 
Extending  from  this  gabbro  is  a  low-lying  outcrop  of  a  foliated  blue  rock 
that  is  decidedly  different  in  texture.  It  is  much  coarser,  and  contains 
considerable  biotite,  suggesting  on  the  surface  a  biotite  schist.  A  micro- 
scopical examination  of  thin  sections  of  this  rock  shows  it  to  be  composed 
of  the  following  minerals :  hornblende,  biotite,  sgirine,  olivin,  titanite  and 
leucoxene  in  the  form  of  titaniferous-magnetite  simple-twinned  orthoclase, 
some  plagioclase,  having  fine  multiple-twinning  and  extinction  of  albite, 
nepheline,  and  sodalite  with  micro-zircons  and  apatite  crystals  in  the 
feldspars.  (See  Fig.  94.)  As  this  rock  contains  nepheline  it  therefore 
bears  the  same  relation  as  the  Essexites  to  the  nepheline  syenites.  It  is 
a  basic  rock  and  in  this  respect  is  similar  in  appearance  to  Essexite,  save 
that  it  is  foliated,  but  it  varies  decidedly  from  the  Essexite  in  that  it 
contains  olivin,  which  would  class  it  in  the  foyaitic  series.  For  this  foli- 
ated basic  nepheline  rock,  the  name  Salemite  is  proposed,  and  has  been 
used  since  1896. 

Associated  with  all  of  the  other  forms  are  masses  and  streaks  which  are 
foliated  and  schistose  having  all  the  appearance  of  crystallized  sediments. 
That  these  masses  are  remnants  of  original  flows  in  the  then  unconsoli- 
dated magma  of  the  nepheline  syenite  is  plainly  evident  by  comparing 
them  with  certain  well-known  Cambrian  crystalline  sediments,  such,  for 
instance,  as  those  at  Naugus  Head  on  the  Marblehead  shore,  Woodbury's 
point  on  the  Beverly  shore,  and  the  cove  on  the  west  shore  of  Great  Misery 
island,  which  are  cut  by  masses  and  veins  of  this  syenite  containing  large 
inclusions  and  fragments  of  these  Cambrian  rocks  with  perfect  outline. 
By  these  examples  it  will  be  seen  at  once  that  the  former  schistose  rocks 
are  totally  unlike  the  latter,  and  could  not  be  mistaken  for  them.  Other 
causes  of  variation  in  these  syenites  are  due  in  part  to  the  acidic  or  basic 
quality  of  the  magma  at  the  time  of  cooling  and  crystallization. 

On  Salem  Neck,  at  the  right-hand  side  of  the  road  to  the  Willows,  there 


Fig.  93.  — PHOTOMICROGRAPH    OF    ESSEXITE    FROM    SALEM    NECK. 


Fig.  94.  —  PHOTOMICROGRAPH    OF    SALEMITE    FROM    SALEM    NECK. 


NEPHELINE    SYENITE  189 

is  an  outcrop  of  Salemite  in  a  field  near  a  small  pond.  The  rock  is  dark- 
gray  to  bluish  in  color,  and  has  a  granitic  structure.  The  outcrop  is  only 
twenty  feet  long  and  ten  feet  wide,  and  in  the  center  the  structure  is  foli- 
ated or  schistose,  the  outer  portion  being  quite  massive  without  any  foli- 
ation.    The  microscopical  stmcture  is  as  follows : 

Augite,  segirine,  brown  hornblende,  red  mica,  hornblende,  var.  arfvedsonite, 
orthoclase,  and  a  plagioclase  that  has  the  fine  multiple-twinning  of  albite.  Sodalite, 
nepheline,  some  titaniferous  magnetite,  apatite,  and  micro-zircons.  These  minerals 
are  in  elongated  and  rounded  grains,  with  biotite  plates  formed  in  the  line  of  the 
schistosity  of  the  rock-mass.  The  large  feldspars  are  in  nearly  perfect  crystals,  and 
are  honeycombed  and  filled  with  elongated  and  rounded  grains  of  the  ground-mass 
which  has  punctured  the  crystals.  One  good  basal  section  of  apatite  has  a  fine 
bubble  inclusion,  and  also  inclusions  of  original  glass.  Many  of  the  simple-twinned 
feldspars  are  perthite.  Some  of  them  have  a  brecciated  structure,  having  been 
punctured  by  the  ground-mass.     Much  of  the  nepheline  is  interstitial. 

Nepheline  Syenite.  —  Nepheline  syenite  is  an  acid  rock  containing 
nepheline.  In  any  typical  outcrop,  forms  will  be  found  in  the  rock-mass 
which  are  clearly  due  to  local  variation.  The  type  is  a  coarse  feldspathic 
rock,  in  which  the  nepheline  and  sodalite  are  seen  in  large  blebs  and  patches 
with  numerous  macroscopic  zircon  crystals,  some  of  which  are  one  fourth 
of  an  inch  long,  with  perfect  double  pyramidal  fades.  (See  Fig.  96.)  In 
thin  section,  when  studied  with  the  microscope  in  polarized  light,  the 
feldspars  are  seen  to  be  composed: 

First,  of  large,  irregular  crystalline  intergrowths  of  microline  and  albite,  and 
second,  of  areas  of  orthoclase  with  occasional  crystals  of  well-twinned  plagioclase, 
probably  Labradorite.  The  orthoclase  is  often  filled  with  microliths  of  a  dust-like 
character.  In  close  proximity  to  the  zircons,  rhombic  sections  are  often  seen  of  a 
mineral  of  a  yellowish-green  color  which  is  isotropic,  and  as  yet  is  undetermined. 
There  are  also  occasional  crystals  and  grains  of  segirine  which  show  a  pleochroism 
varying  from  blue-green  to  a  yellowish-green,  and,  with  the  quartz  wedge  as  de- 
termined by  the  negative  bisectrix,  make  an  angle  of  4°  or  5°  with  the  vertical  axis. 
Some  augite  is  present,  showing  brilliant  colors  in  the  basal  section,  also  brown 
hornblende,  much  perfectly  red  biotite,  and  some  magnetite.  In  the  microscopic 
investigation  of  loose  grains,  the  specific  gravity  of  the  minerals  of  the  crushed 
rock,  when  passed  through  the  90  mesh  sieve  and  separated  in  the  Thoulet  solu- 
tion, gives  the  following  portions  as  determined  by  the  Westphal  balance  :  Specific 
gravity  2.75  separated  the  mica  hornblende,  augite,  zircon,  and  magnetite  ;  2.726 
removed  some  remaining  scales  of  biotite  with  Labradorite  ;  2.614,  elasolite,  plagio- 
clase, and  albite  ;  2.595,  microcline  and  albite,  which  forms  the  largest  proportion 
of  the  crushed  rock  ;  2.585,  orthoclase  and  microcline,  leaving  sodalite  and  ortho- 
clase as  the  residue. 


190  QUARTZ    AUGITE    SYENITE    OR    AKERITE 

Outcrops  of  nepheline  syenite  occur  on  Salem  Neck,  south  and  east  of 
the  pest-house,  and  extend  to  Fort  avenue.  Other  outcrops  appear  on 
Winter  island.  Great  Haste  rock  is  largely  composed  of  this  formation,  and 
on  Misery  island,  outcrops  appear  on  both  sides  of  "the  harbor,"  and  also 
on  the  eastern  side  of  the  island,  north  of  the  outer  cove.  On  the  western 
side  of  the  island,  there  are  eleven  outcrops,  and  on  the  extreme  south- 
eastern point  is  an  outcrop  in  which  nepheline  and  sodalite  occur. 

Quartz  Augite  Syenite  or  Akerite.  —  The  determinations  of  the  min- 
erals in  this  rock,  studied  in  thin  sections  with  the  polarizing  microscope 
(see  Fig.  97),  are  as  follows:  Orthoclase,  brown  hornblende,  red  mica 
(probably  phlogopite),  much  titanite,  numerous  fine  sections  of  augite, 
several  small  crystals  of  apatite,  a  few  small  zircons,  one  section  of  micro- 
cliae  in  one  of  the  slides,  Baveno  twin-crystals  of  orthoclase  which  show 
the  intergrowth  of  albite  as  microperthite.  The  augite  is  often  sur- 
rounded by  magnetite,  and  dust-lrke  inclusions  of  magnetite  in  the  ortho- 
clase give  this  syenite  its  dark  color.  In  some  of  the  sections  from  the 
outcrop  at  Prospect  street,  Gloucester,  there  are  some  quartz  blebs,  but 
the  rock  as  a  whole  is  poor  in  quartz,  and  resembles  the  syenites  of  Cham- 
wood,  England.^ 

Augite  syenite  outcrops  beside  the  road,  south  of  Hawkes'  brook  in 
South  Lynnfield,  and  occasional  outcrops  may  be  seen  for  about  one  half 
of  a  mile,  on  both  sides  of  Salem  street. 

In  the  Robin  Rock  granite  quarry.  South  Lynnfield,  the  rock-mass  is  a 
typical  hornblende  granite,  but  the  rock  in  the  older  part  of  the  quarry  at 
the  south  side  is  without  quartz,  and  is  therefore  a  form  of  augite  syenite. 
Between  Wyoma  and  Mount  Spicket  in  the  Lynn  woods,  are  numerous 
exposures  of  quartz  augite  syenite,  which  extend  to  the  northern  end  of 
Wyoma  lake.  Dikes  of  syenite,  six  to  ten  inches  in  width,  cut  the  diorite 
in  the  western  part  of  Salem.  These  dikes  resemble  an  akerite  syenite 
but  without  quartz.  Such  a  dike  outcrops  on  a  high  diorite  ledge  over  a 
mile  from  Salem  Neck.  The  highest  points  in  the  County  where  the 
syenite  rocks  occur  are  Briscoe  hill  and  Poorhouse  hill  in  Beverly. 
On  Briscoe  hill  the  rock  is  a  coarse  akerite  at  the  east  and  south,  and  a 
nepheline  syenite  at  the  west.  Poorhouse  hill  is  a  quartz  hornblende 
syenite. 

A  mile  west  from  Curtis'  point,  Beverly,  are  outcrops  of  augite  syenite. 
Outcrops  are  also  numerous  in  Montserrat  woods,  southeast  from  the 
Salem  reservoir  hill.     There  is  also  an  exposure  on  the  Beverly  shore, 

'  Quarterly  Journal  of  the  Geological  Society,  Vol.  XXXIV,  p.  215. 


Fig.  95.  — BIOTITE    TINGUAITE    DIKE    IN    AUGITE    SYENITE    LEDGE,    MANCHESTER. 


Fig.  96.  — NEPHELINE    SYENITE    WITH    VEINS    OF    PULASKITE    AND    HORNBLENDE    GABBRO ' 

ALSO    SHOWING    EROSION    OF    BOULDERS    IN   SITU. 

Cat  Cove,  Salem  Neck. 


QUARTZ    AUGITE    SYENITE    OR    AKERITE  193 

fifty  yards  east  of  Mingo  beach,  which  extends  to  Tuck's  point  and  north- 
erly to  a  large  outcrop  south  of  Beverly  common.  On  Briscoe  hill  the 
rock  is  a  coarse  augite  syenite,  cut  by  veins  of  pulaskite.  Outcrops  occur 
in  the  Hale  Street  cemetery  and  on  Poorhouse  hill.  On  Coming  street, 
Beverly,  are  other  outcrops  of  the  same  rock. 

Bald  hill,  Beverly,  is  composed  entirely  of  augite  syenite,  in  various 
forms,  coarse  and  fine.  The  microscopical  structure  of  several  of  the 
above  named  outcrops  is  as  follows : 

Thin  sections  prepared  from  specimens  collected  in  an  old  quarry  on  the  W.  D. 
Pickman  estate  at  Beverly  cove  :  numerous  large  porphyritic  crystals  of  microcline- 
microperthite '  (see  Fig.  98),  some  multiple-twinned  plagioclase,  probably  Labra- 
dorite,  much  orthoclase,  augite  in  two  forms,  one  in  large,  ragged  crystals,  and  the 
other  in  long,  needle-shaped  crystals  inclosed  in  the  feldspars  as  microliths,  numer- 
ous small,  ragged  crystals  of  segirine,  some  brown  hornblende,  red  biotite  in  large 
patches,  numerous  perfect  zircon  crystals,  fine  sections  of  nepheline,  some  apatite 
and  magnetite,  with  a  ground-mass  of  thin  films  of  quartz. 

Sections  prepared  from  the  outcrop  on  the  east  side  of  Briscoe  hill,  in  Beverly, 
are  of  similar  composition,  but  contain,  in  addition,  olivin  and  titanite.  At  the 
ledge  used  for  road-building  purposes  on  Poorhouse  hill,  there  are  two  well-marked 
forms.  One  is  rich  in  hornblende,  contains  little  augite  and  has  much  quartz,  not 
only  as  a  ground-mass,  but  also  as  distinct  patches,  with  fine,  large  crystals  of  niicro- 
cline-microperthite  (the  soda-microcline  of  Professor  Brogger),  some  sgirine  crys- 
tals, apatite  and  magnetite.  The  other  is  rich  in  augite,  has  considerable  quartz, 
some  hornblende,  biotite,  asgirine,  and  nepheline.  The  first,  except  for  the  segirine 
and  microcline-microperthite,  would  be  classed  as  hornblende  granitite.  The  other 
is  nearly  if  not  quite  like  the  typical  augite  syenite.  In  this  last  a  vein  of  pyrrho- 
tite  of  a  rich  yellow-bronze  color  is  seen,  which  carries  a  small  percentage  of  nickel. 
Molybdenite  also  occurs  in  this  outcrop. 

North  of  Long  hill,  Manchester,  are  several  outcrops  of  augite  syenite, 
and  one  opposite  the  West  Parish  meeting-house,  Gloucester,  is  quite  basic 
and  schistose.  A  blue  pulaskite  outcrops  opposite  the  store  of  William  Rust, 
and  farther  west  on  the  Essex  road  other  outcrops  may  be  seen.  All  of 
the  exposures  west  of  Haskell's  mill  brook,  from  Lufkin  street  to  the  shore 
at  Conomo  point,  are  augite  syenite,  which  is  also  the  bed-rock  of  Cross' 
island.  From  Conomo  point  to  the  Essex  town-farm,  all  the  outcrops  are 
of  the  same  character,  in  fact,  this  is  the  prevailing  rock  from  Coy's  pond 
in  Wenham  to  Thompson's  village  in  South  Essex. 

Southeast  of  Moses'  mountain  in  North  Yarmouth,  Manchester,  the 
outcrops  are  quartz  hornblende  syenite,  in  which  the  hornblende  is  a  form 

1  This  form  of  feldspar  is  characteristic  of  Professor  Brogger' s  microcline-microper- 
1;hite  in  the  augite  syenite  rocks  of  Norway.  — Brogger,  Min.  der  Syenite  Py.,  p.  627. 


194  QUARTZ    AUGITE    SYENITE    OR    AKERITE 

of  arfvedsonite.  The  ledge  used  by  the  town  for  road  material  in  1899 
is  the  same  rock.  From  Lobster  cove  to  Gale's  point,  and  northerly 
into  Manchester  harbor,  all  the  outcrops  are  syenite,  largely  akerite  and 
segirine  syenite.  The  Ram  islands,  Chubb's  island,  and  House  island  are 
augite  syenite.  On  the  higher  part  of  Misery  island,  on  the  west  side, 
is  an  outcrop  of  nordmarkite  with  wide  dikes  of  solvsbergite.  On  the 
shores  of  the  island  are  numerous  basic  dikes  cutting  the  more  massive 
rock  of  the  island. 

Within  the  city  limits  of  Gloucester,  bounded  on  the  north  by  Warner 
street,  and  extending  several  hundred  yards  on  Prospect  street,  to  the 
south  and  southwest,  is  a  large  mass  of  augite  syenite.  Occasional  out- 
crops are  also  seen  south  of  this  in  East  Gloucester,  near  Bass  rocks,  and 
in  the  cove  in  Gloucester  harbor  west  of  Ocean  pond,  which  embraces 
the  larger  part  of  Eastern  point.  In  a  westerly  direction,  there  are  out- 
crops near  Goose  cove,  Annisquam.  One  large,  dome-shaped  mass  near 
the  comer  of  Quarry  street.  Bay  View,  is  of  a  coarser  texture  and  greener 
in  color,  and  resembles  the  augite  syenite  of  Essex  and  Manchester.  From 
this  last-named  outcrop  to  the  northeast  side  of  Plum  cove,  Lanesville, 
there  are  numerous  exposures  in  old,  deserted  quarries,  and  one  especially 
good  section  is  seen  by  the  roadside  opposite  Young  avenue,  Lanesville. 
The  trend  or  strike  of  all  of  the  outcrops  is  in  the  usual  direction,  N.N.E. 
to  S.W. 

This  entire  outcrop  is  some  twelve  miles  long,  and  from  a  few  rods 
wide  in  Hamilton  to  six  miles  in  Essex  and  Manchester,  the  latter  width 
continuing  across  Gloucester  from  Lanesville  to  Eastern  point.  A  massive 
ridge  of  augite  syenite  extends  from  opposite  Rocky  neck  to  Bass  avenue, 
and  also  outcrops  at  the  cove  near  Niles'  pond.  At  Wonson's  cove  and  at 
Smith's  cove  this  syenite  is  exposed  below  the  road  wall,  where  it  is  sur- 
rounded by  beach  sand.  The  feldspar  crystals  are  large  and  very  perfect, 
giving  the  surface  of  the  outcrops  a  porphyritic  appearance.  The  bed- 
rock on  Warner  street  is  an  augite  syenite  in  appearance,  but  megascopi- 
cally  it  resembles  segirine  syenite  at  Gale's  point,  Manchester.  This  form 
is  entirely  distinct  from  the  quartz  augite  syenite  on  Prospect  street.'  A 
massive  outcrop  of  syenite  occurs  near  Dike  street,  and  is  used  for  road 
materia^.  It  is  deep  blue  in  color,  and  is  identical  with  the  blue  pulaskite 
of  Professor  Williams.  Another  outcrop  of  this  rock  may  be  seen  in  the 
railroad  cutting  east  of  the  Magnolia  station.     In  the  area  between  Fresh- 

>  The  Petrological  Province  of  Essex  County,  Journal  of  Geology,  Vol.  VI,  p.   789. 


Fig.  97.  — PHOTOMICROGRAPH    OF   AUGITE    SYENITE,    OR   AKERITE. 
South  Salem. 


^■m'fti 


■Fig.  98.— PHOTOMICROGRAPH    OF    MICROCLINE    CRYSTAL  AUGITE    SYENITE    FROM    BRISCOE    HILL, 
BEVERLY,    SHOWING    ALBITE    INTERGROWTHS   ACROSS   THE  TWINNED    MICROCLINE. 


QUARTZ    AUGITE    SYENITE    OR    AKERITE  197 

water  Cove  village,  Gloucester,  and  extending  southwesterly  to  the  Mag- 
nolia station,  the  outcrops  of  augite  syenite  are  one  half  of  a  mile  wide. 

At  the  augite  syenite  outcrop  in  Brace's  cove,  East  Gloucester,  and  by 
the  roadside  on  the  sand-beach  near  the  Niles'  farm  buildings,  on  the 
southwest  side  of  Eastern  point,  the  large,  almost  perfect,  tabular  feld- 
spar crystals  give  this  rock  a  very  striking  appearance.  The  micro- 
scopic structure  of  thin  sections,  when  studied  with  the  polarizing  micro- 
scope, shows  the  following  minerals  in  its  composition: 

Much  augite,  green  hornblende,  glaucophane  and  chlorite  as  secondary 
products  in  the  decomposition  of  the  hornblende,  microliths  of  segirine, 
one  characteristic  crystal  of  hypersthene,  magnetite,  limonite,  numerous 
zircon  and  apatite  crystals,  orthoclase,  microcline-microperthite,  some 
plagioclase,  and  a  little  quartz  as  the  ground-mass.  The  large  tabular 
porphyritic  crystals  of  feldspar  are  microcline-microperthite.  The  out- 
crop of  this  augite  syenite,  in  the  marsh  near  the  poor-farm,  used  by  the 
city  of  Gloucester  for  road-making,  is  of  a  very  dark  color,  and  a  macro- 
scopical  examination  would  indicate  it  to  be  diorite,  but  the  microscopi- 
cal structure,  as  seen  in  thin  sections,  shows  it  to  be  composed  of  augite, 
asgirine,  hornblende,  limonite,  some  biotite,  orthoclase,  microcline-micro- 
perthite, zircons,  apatite,  magnetite  and  a  little  quartz  as  a  cement  in 
the  ground-mass,  making  the  rock  a  typical  augite  syenite.  Numerous 
thin  sections  have  been  prepared  from  all  parts  of  the  outcrops  of  this 
augite  syenite  described  above.  In  specimens  from  the  comer  of  Warner 
and  Prospect  streets  in  the  city  of  Gloucester,  the  microscopical  structure 
is  quite  characteristic  of  this  rock-mass.  They  all  contain  augite,  asgirine, 
titanite,  microcline-microperthite,  with  some  quartz.  Some  of  the  sections 
contain  nepheline,  and  one  section  contains  an  excess  of  the  fine  multiple- 
twinned  albite  (sp.  gr.  2.63).  There  is  more  or  less  orthoclase,  horn- 
blende, biotite,  and  magnetite  with  crystals  of  zircon  and  apatite  as  in- 
clusions in  the  feldspars. 

Several  thin  sections  of  the  rock  in  the  massive  outcrop  near  Magnolia 
station,  and  in  the  railroad  cutting  one  hundred  yards  east  of  the  station, 
when  studied  with  the  polarizing  microscope,  were  found  to  be  composed 
of  microcline-microperthite,  well-twinned  plagioclase,  orthoclase,  augite, 
green  hornblende,  red  biotite,  zircons,  apatite,  fine  sections  of  titanite, 
much  magnetite,  some  limonite,  nepheline  and  isotropic  sections  of  sodalite 
which  gelatinized  readily  with  hydrochloric  acid.  Some  sections  also  con- 
tained regular  crystals  of  hypersthene  and  some  well-formed  crystals  of 
olivin.      In  one  of  the  sections  there  were  large  patches  of  elseolite.     The 


198  QUARTZ    AUGITE    SYENITE    OR    AKERITE 

color  of  the  whole  rock-mass  in  fresh  hand  specimens  is  dark  grayish  and 
green.  This  rock  is  quite  distinct  from  any  member  of  the  nepheline- 
zircon-syenite  group  heretofore  described,  inasmuch  as  it  contains  hypers- 
thene  and  olivin  without  a  glassy  ground-mass,  and  it  is  equally  distinct 
from  the  typical  augite  syenite  of  Vom  Rath. 

On  Main  street,  Lanesville,  opposite  Young  avenue,  is  an  outcrop  of 
augite  syenite,  and  other  outcrops  fringe  the  shore  from  Annisquam  to 
Squam  harbor.  Sections  from  the  Lanesville  outcrop,  opposite  Young 
avenue,  contain  olivin.  In  some  of  the  sections,  serpentine  has  developed 
in  the  cleavage  cracks,  and  some  of  the  feldspars  have  the  microscopical 
characters  common  to  anorthoclase,  extinguishing  by  sections  and  in 
patches.  This  is  the  soda-microcline  of  Professor  Brogger.'  One  section 
shows  multiple-twinned  albite  intergrowths  directly  across  the  twinned 
microcline,  giving  it  a  very  beautiful  appearance  when  seen  in  polarized 
light.  There  are  also  numerous  irregular  fragments  of  aegirine  and  a  few 
small,  triangular  patches  of  nepheline  with  a  ground-mass  of  quartz  as  a 
cement.  Several  interesting  dikes  in  this  vicinity  cut  the  granite  and 
syenite  rocks.  A  solvsbergite  dike  at  Andrews'  point  cuts  hornblende 
granite,  and  a  third  of  a  mile  east  from  Squam  lighthouse  are  several  wide 
dikes  of  tinguaite  and  quartz  syenite  porphyry.  Within  two  hundred 
yards  of  the  light,  there  is  a  biotite  tinguaite  dike. 

Dikes  and  masses  of  Labradorite  gabbro  occupy  the  greater  part  of 
Davis'  neck,  Bay  View.  It  is  a  very  conspicuous  rock  with  crystals  of 
Labradorite,  some  of  which  are  two  inches  wide,  and  from  three  to  six 
inches  in  length. 

The  Dry  Salvages  or  Tri-Salvages,  and  the  Little  Salvages,  islands 
east  from  Sandy  Bay,  are  outcrops  of  hornblende  syenite  having  little 
or  no  quartz.  The  larger  number  of  the  outcrops  on  the  north  side  of 
Gap  Head  and  Straitsmouth  island  are  syenite,  with  some  areas  of  micro- 
graphic  granite.  In  a  southwesterly  course  from  Gap  head  to  the  Rock- 
port  pumping  station,  extending  on  both  sides  of  Cape  pond,  all  the  out- 
crops are  augite  syenite. 

From  Bass  Rocks,  Gloucester,  to  Cobblestone  beach,  the  outcropping 
bed-rock  is  quartz  syenite,  porphyry,  and  aplite.  From  Brace's  cove, 
westerly  across  Eastern  point  to  East  Main  street,  all  the  outcrops  are 
augite  syenite.  Thatcher's  island  has  about  eighty  acres  of  surface,  and 
is  a  massive  outcrop  of  augite  syenite  cut  by  several  basic  dikes.  The 
augite  syenite  outcrops  at  Emerson's  point  on  the  mainland  opposite  the 
'  Zeitschrift  fur  Krystallographie,  Vol.  XVI,  p.  261. 


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3 

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Hffi 

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jl 

^^^^^IH 

^Bi  ^    ^ 

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Fig.   99.  — PULASKITE    SYENITE    FORMED    INTO    BOULDERS  W   SITU    BY    DISINTEGRATION    AND    EROSION. 

Salem  Neck. 


Fig.    100.-   PULASKITE    SYENITE    VEINS    CUTTING    DECAYED    HORNBLENDE    GABBRO. 
Salem    Neck. 


PULASKITE  201 

island,  and  also  on  the  north  shore  of  Loblolly  cove.  Probably  this  akerite 
bed-rock  is  continuous  under  the  sea  from  the  mainland  to  Thatcher's 
island. 

Pulaskite.  —  This  formation  varies  from  the  augite  syenite  or  akerite 
in  that  it  contains  little  or  no  nepheline.  (See  Figs.  99,  100.)  In  some 
places,  noticeably  in  outcrops  on  the  Beverly  shore  at  Curtis'  point, 
it  becomes  distinctly  a  hornblende  zircon  syenite.  Here  the  feldspars  are 
microperthitic  intergrowths  of  albite  and  plagioclase,  with  a  large  pro- 
portion of  magnetite.  Still  farther  to  the  eastward,  along  the  coast,  at 
Gale's  point  on  the  Manchester  shore,  occur  veins  of  syenite  rock,  from  a 
few  inches  to  two  feet  in  width,  which  the  author  has  described  as  aegirine 
syenite,  for  these  veins  are  completely  filled  with  acicular  segirine  crystals, 
some  of  which  are  two  inches  long  and  one-sixteenth  of  an  inch  wide. 
The  feldspar  in  this  rock  has  the  optical  character  of  anorthoclase.  North 
of  Fort  Lee,  on  Salem  Neck,  the  pulaskite  becomes  slightly  massive  in  a 
ledge  which  was  opened  during  the  construction  of  the  fort.  West  from 
this  opening  are  two  exposures  of  pulaskite,  having  little  or  no  hornblende. 
On  the  Beverly  shore  from  Mackerel  cove  to  Woodbury's  point,  the  syenite 
rock  is  largely  pulaskite  and  a  coarse  akerite.  Beyond  the  point,  the  out- 
crops are  pulaskite,  and  extend  to  the  western  end  of  West's  beach. 

Nordmarkite.  —  This  is  a  mica  hornblende  quartz  syenite  rock,  and 
was  so  named  by  Professor  Henry  S.  Washington  of  New  Jersey.  Its  micro- 
scopical structure  shows  augite  syenite  minerals,  microcline-microperthite, 
and  the  soda-microcline,  which  are  characteristic  minerals  described  by 
Professor  Brogger  as  occurring  in  the  augite  syenite  rocks  of  Norway. 

There  are  outcrops  of  this  rock  on  both  sides  of  Lobster  cove,  Annis- 
quam,  extending  for  a  third  of  a  mile.  It  is  also  massive  in  West  Gloucester, 
with  many  large  outcrops.  (See  Figs.  loi,  102.)  The  trend  of  the  out- 
crops from  Essex  avenue,  West  Gloucester,  to  Lobster  cove,  Annisquam, 
is  northeast  to  southwest,  which  is  parallel  to  the  prevailing  strike  of  the 
sedimentary  beds.  A  narrow  vein  of  nordmarkite  extends  southerly  near 
the  creek  by  Essex  avenue,  beyond  the  railroad  track,  and  an  outcrop 
may  be  seen  near  the  cellar  of  the  Russia  Cement  works.  The  south- 
eastern extension  of  this  rock  is  seen  in  large  outcrops  on  both  sides  of 
the  railroad  near  the  Anchor  Forge  and  Iron  Works,  and  on  Rocky  Neck, 
East  Gloucester. 

Thin  sections  prepared  from  specimens  collected  on  Pierce's  island  in  Squam 
river  (see  Pig.  103),  have  the  following  mineral  composition  :  Nos.  i,  2,  3,  contain 
numerous  patches  of  red  biotite,  hornblende,  and  augite,  in  perfect  crystal  form. 


202  SOLVSBERGITE 

microcline,  orthoclase,  microcline-microperthite,  and  numerous  inclusions  of  zircons, 
apatite,  and  magnetite,  the  whole  cemented  in  a  ground-mass  of  quartz.  Thin  sec- 
tions prepared  from  specimens  collected  in  an  old  and  deserted  quarry  on  the  north- 
east side  of  this  island  are  much  more  porphyritic.  The  larger  crystals  are  always 
microcline-microperthite  (sp.  gr.  2.60  to  2.64).  One  of  the  sections  has  fine 
crystals  of  titanite,  and  the  quartz  is  in  thinner  films  as  a  ground-mass  or  cement, 
otherwise  the  minerals  are  of  a  similar  character  to  Nos.  i,  2,  3.  Sections  from  an 
outcrop  by  the  side  of  the  road  leading  to  Coffin's  beach,  near  a  deserted  quarry  in 
West  Gloucester,  are  of  a  fine-grained  rock,  slightly  porphyritic,  with  an  abundance 
of  biotite,  perfect  well-twinned  crystals  of  albite,  much  microcline  in  large,  irregular 
patches,  microcline-microperthite,  hornblende,  augite,  and  titanite,  some  of  the 
orthoclase  feldspars  having  areas  of  micropegmatite.  From  the  great  abundance 
of  biotite  in  this  rock -mass  it  may  be  locally  called  a  biotite  nordmarkite  (sp.  gr.  of 
feldspars  in  this  rock,  2.57  to  2.62).  Thin  sections  from  the  augite  syenite  outcrop 
at  Wheeler's  point,  Gloucester,  and  extending  to  Goose  cove,  Annisquam,  and  Bay 
View,  give  the  microscopic  structure  as  follows:  Nos.  i,  2,  Wheeler's  point,  numer- 
ous large  porphyritic  crystals  of  microcline-microperthite,  albite  and  orthoclase, 
good  crystals  of  augite,  hornblende,  numerous  crystals  of  titanite,  some  biotite, 
magnetite,  a  little  quartz,  some  crystals  of  apatite  and  zircons.  No.  3,  section  from 
Goose  cove,  is  the  same  as  the  last.  Nos.  4,  5,  6,  sections  from  Bay  View  quarries, 
contain  augite  and  segirine.  In  one  section.  No.  5,  there  is  a  complete  felting  of 
these  ffigirine  crystals  which  sink  to  the  finest  dust  as  inclusions  in  the  microcline- 
microperthite,  giving  the  rock  a  deep  green  color. 


Solvsbergite.  —  The  Bostonite  porphyry  (Rosenbusch)  on  Coney  Island, 
is  known  now  as  solvsbergite,  the  name  having  been  first  applied  by 
Professor  Henry  S.  Washington  of  New  Jersey.  Naugus  head,  on  the 
Marblehead  shore,  is  largely  composed  of  metamorphosed  Cambrian  sedi- 
mentary rocks  cut  by  veins  and  large  dikes  of  pulaskite  syenite  and  solvs- 
bergite, which  extend  to  Peach's  point  and  Orne's  island. 

Coney  island  and  the  Coney  island  ledges  are  largely  composed  of  a  coarse 
pegmatitic  mass  of  microcline-microperthite  in  which  the  albite  equals  the 
microcline  in  volume.  There  are  also  coarse  plates  of  biotite  and  small 
zircons,  the  latter  held  as  inclusions  in  both  the  soda-microcline  and  the 
biotite.  Pulaskite  syenite  and  hornblende  gabbro,  with  numerous  dikes, 
are  also  present.  A  large  dike  of  vesicular  basalt,  the  vesicles  being  filled 
with  crystals  of  epidote,  cuts  across  the  island  from  northwest  to  south- 
east. Other  interesting  dikes,  not  yet  determined,  cut  the  pulaskite  and 
gabbro  rocks. 

Great  Haste  rock  and  the  Haste  ledges  are  nepheline  syenites  contain- 
ing nepheline,  sodalite,  zircons,  and  much  titaniferous  magnetite. 

A  dike  of  solvsbergite,   cutting  the  hornblende  granite  at  Andrews' 


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Fig.    101,  — NORDMARKITE    LEDGE    BROKEN    DOWN    BY    ACTION    OF    FROST. 
West  Gloucester. 


Fig.    102.  — QUARRY    OPENED    IN    A    LEDGE    OF    NORDMARKITE,    SHOWING    IRREGULAR    JOINTING 
OF    THE    ROCK.     WEST  GLOUCESTER. 


BIOTITE    TINGUAITE  205 

point,  the  northeastern  extremity  of  Cape  Ann,  has  been  analyzed  by 
Professor  H.  S.  Washington  as  follows : 

SiOj 64.28 

TiOj 0.50 

AP^Oj 15.97 

FeA      2.91 

FeO 3.18 

MnO traces 

MgO 0.03 

CaO ■    ■    ■  0.85 

Na  O      7.28 

K3O 5.07 

HjO  ig 0.20 

100.27 
Specific  gravity,  2.703  at  22°  Cent. 

Biotite  Tinguaite.  —  At  Manchester,  on  Gale's  rocks,  two  hundred  yards 
south  of  Gale's  point,  near  low-water  mark,  there  is  a  dike  of  a  very  pe- 
culiar color.  (See  Fig.  95.)  It  is  six  inches  wide,  and  is  exposed  for 
twenty  feet.  It  cuts  the  augite  syenite  in  a  nearly  horizontal  position 
six  feet  below  the  surface  of  the  syenite  mass.  This  outcrop  is  only  ex- 
posed to  view  at  low  water.  On  the  surface  the  color  is  a  grayish-green, 
mottled  with  bluish-black  spots.  A  freshly  broken  surface  is  of  an  olive- 
green  color,  and  the  spots  are  black.  Its  occurrence  in  the  immediate 
region  of  the  segirine  tinguaite  dike  at  Pickard's  point  and  the  ffigirine 
syenite  at  Gale's  point,  attaches  to  this  rock  a  special  interest.  A  micro- 
scopical examination  gave  the  following  minerals  in  its  composition: 
aggirine,  nepheline,  sodalite,  biotite,  a  triclinic  feldspar,  microperthite,  and 
some  larger  feldspars  that  gave  optical  characters  suggesting  anorthoclase, 
and  having  nearly  the  same  structure  as  the  anorthoclase  phenocrysts  in 
the  keratophyre  rock  from  Marblehead  harbor.  The  black  spots  in  the 
rock  were  magnetic  iron,  a  decomposition  product  of  an  original  biotite. 
Dr.  A.  S.  Eakle  of  Harvard  University  made  the  following  microscopical 
and  chemical  analysis  of  the  rock: 

The  rock  is  composed  mainly  of  feldspathic  laths  and  plates  with  much 
nepheline  and  less  amounts  of  segirine,  magnetite,  and  biotite.  A  little 
sodalite,  apatite,  and  zircon  are  also  present.  The  feldspars  have  a  fib- 
rous appearance  caused  by  lamellar  intergrowths  of  the  soda  and  potash 
feldspars,  microcline  and  albite,  forming  microcline-microperthite.  Carls- 
bad twinning  of  the  laths  is  common.     Nepheline  occupies  the  position  of 


206  BIOTITE    TINGUAITE 

a  filling  matter  in  the  interspaces  formed  by  the  feldspars.  The  nepheline 
has  altered,  and  is  present  as  grayish,  muddy,  granulated  sections,  which 
are  apparently  mixtures  of  nepheline  with  kaolin  and  very  fine  grains  of 
quartz,  ^girine  is  disseminated  in  the  rock  in  fragments  and  small 
crystals,  in  sufficient  amount  to  give  it  its  greenish  cast,  shading  from 
deep  grass-green  to  an  almost  colorless  appearance.  Magnetite  is  promi- 
nent, and  marks  the  remains  of  rather  large  plates  of  a  former  dark  silicate. 
Most  of  the  original  silicate  has  completely  disappeared,  leaving  only  the 
patches  of  black  oxide  of  iron;  but  in  an  occasional  section,  a  greenish- 
brown  silicate  still  remains  between  the  black  borders  of  magnetite,  which 
from  its  absorption,  parallel  extinction,  and  characteristic  shimmer,  is  evi- 
dently biotite.  Sodalite  is  present,  and  also  a  few  small  crystals  of  apatite 
and  zircon  as  inclusions  in  the  feldspars. 

The  tinguaite  dike  at  Pickard's  point,  Manchester,^  contains  much 
analcite,  and  is  classified  as  analcite  tinguaite.  Very  little  isotropic  min- 
eral occurs  in  the  dike  here  described,  and  from  its  appearance  and  the 
presence  of  chlorine,  what  is  present  is  judged  to  be  sodalite,  so  the  dike 
can  hardly  be  classed  with  the  one  at  Pickard's  point.  The  structure  of 
the  rock  also  differs  in  that  the  component  minerals  do  not  occur  in  needle 
forms,  but  in  much  stouter  lath-shapes,  showing  a  greater  degree  of  crys- 
tallization of  the  individual  minerals,  and  producing  a  much  less  dense  phase 
of  tinguaite.  The  presence  of  many  plates  of  feldspar  tabular  to  M  indi- 
cates an  approach  to  a  solvsbergite,  and  the  rock  might  perhaps  with 
equal  right  be  considered  a  phase  of  a  nepheline  solvsbergite.  It  seems  in 
structure  and  composition  to  lie  intermediate  between  a  nepheline  tinguaite 
and  a  nepheline  tegirine  solvsbergite.     The  analysis  of  the  rock  yields : 

SiOz 60.05 

TiOs  and  ZrOj      o.ii 

AlA      19-97 

FePg 4-32 

FeO 1.04 

MnO 0.79 

CaO 0.91 

MgO 0.23 

K2O 324 

Na^O      769 

HjO  at  no 0.15 

HjO  ig 1.26 

CI 0.28 

100.04 
'  Bulletin  of    Essex  Institute,  Vol.   XXV,   p.  4;  and  American  Journal  Science,  Vol. 
VI,  p.  176. 


Fig.    103.  — PHOTOMICROGRAPH    OF    NORDMARKITE,    GLOUCESTER. 


Fi^.    104.  — PHOTOMICROGRAPH    OF   /EGIRINE   TINGUAITE    FROM    PICKARD'S    POINT,    MANCHESTER. 


^GIRINE    TINGUAITE   OR    ANALCITE    TINGXJAITE  209 

The  specific  gravity  is  2.708.  The  dike  is  difficult  to  reach,  and  the 
specimens  examined  come  from  near  the  surface  and  have  altered  enough 
to  make  it  difficult  to  estimate  the  mineral  contents  with  any  degree  of 
accuracy.^ 

.^girine  Tinguaite  or  Analcite  Tinguaite.  —  Thin  sections  of  this  phono- 
lite  dike  rock,  when  studied  under  the  microscope  in  polarized  light  (see 
Figs.  104,  105,  106),  show  that  it  is  composed  of  some  crystals  of  sodalite, 
hexagonal  in  outline,  and  numerous  long,  irregular  feldspar  phenocrysts, 
which  sometimes  are  in  Carlsbad  twins  with  a  quite  fine  multiple-twinning 
and  in  one  section  there  is  double-twinning  of  the  microcline  structure. 
Several  of  the -feldspar  crystals  have  a  perfectly  square  cross-section  which 
is  very  noticeable,  and  suggests  a  resemblance  to  anorthoclase  phenocrysts. 
Micro-chemical  tests  of  this  feldspar  in  hydro-fluosilicic  acid  give,  upon 
evaporation  of  the  acid,  equal  numbers  of  crystals  of  sodium  (NajO)  and 
potassiiun  (K2O),  but  with  no  calcium  (CaO) ;  specific  gravity  2.572  to 
2.58.  The  analysis  of  the  anorthoclase  feldspars  in  the  keratophyre  rock 
which  was  made  at  the  laboratory  of  the  United  States  Geological  Survey 
at  Washington,  by  Dr.  Thomas  Chatard,  gave  Kfi,  6.98 ;  NajO,  6.56.  This 
micro-chemical  test,  therefore,  shows  that  the  feldspar  in  this  phonolite 
rock  is  very  near  if  not  chemically  equal  to  anorthoclase.  The  hexagonal 
outlines  of  the  sodalite  phenocrysts  are  isotropic,  and  the  mineral  gelat- 
inizes readily  with  acid,  which  upon  evaporation  gives  an  abundance 
of  common  salt  crystals.  There  are  also  some  crystals  of  green  augite 
and  brown  hornblende,  one  of  the  outline  hornblende  crystals  being  filled 
with  minute  crystals  of  gegirine.  The  holo-crystalline  ground-mass  is 
composed  of  feldspars  and  feebly  polarizing  nepheline  in  a  nearly  com- 
plete felting  of  segirine  crystals  and  grains,  some  of  which  sink  to  the 
finest  dust.  These  cegirine  grains  are  so  abundant  in  the  feldspars  of  the 
ground-mass  that  the  specific  gravity  of  the  feldspar  in  the  rock-powder, 
even  after  passing  through  the  100  mesh  sieve,  could  not  be  clearly  made 
out,  but  with  the  inclusions  of  segirine  it  was  as  low  as  2.59.  This  rock- 
powder,  gelatinized  readily  with  acid,  and,  upon  evaporation,  an  abundance 
of  gypsum  crystals  appeared,  thus  characterizing  some  of  the  minerals  in 
the  ground-mass  as  belonging  to  the  haiiyne  group. 

A  chemical  analysis  by  Dr.  Henry  S.  Washington  gave  the  following 
result : 

'   Bulletin  of  Essex  Institute,  Vol.  XXIX,  p.  58. 


210  UMPTEKITE    GABBRO 

SiOz 56.7s 

TiOj 0.30 

AljOg  20.69 

FeA 3.52 

FeO 0.59 

MgO 0.1 1 

CaO 0.87 

NazO      1 1. 45 

K2O 2.90 

CI 0.28 

H2O  110° 0.04 

H2O  110°  +      3.18 

100.68 
Specific  gravity,  2.474  at  22°  Cent. 

Umptekite  Gabbro.  —  On  Salem  Neck,  the  Beverly  shore,  and  on 
Misery  island,  are  masses  and  dikes  of  a  hornblende  gabbro  which  varies 
greatly  in  structure  (see  Figs.  107,  108)  In  the  same  dike,  or  general 
mass,  three  different  types  have  been  found  with  various  intermediate 
grades.  First,  a  compact,  tough,  bluish-white,  feldspathic  mass  containing 
a  few  grains  of  hornblende.  Second,  a  crystalline  rock  composed  of  nearly 
equal  amounts  of  feldspar,  hornblende,  and  titaniferous  magnetite.  Third, 
a  rock  in  which  the  feldspar  becomes  subordinate,  serving  merely  as  a 
matrix  to  hold  large  porphyritic  crystals  of  hornblende,  some  of  which  are 
six  inches  long  and  three  inches  wide.  From  an  analysis  made  by  F.  E. 
Wright,  under  the  direction  of  Professor  Rosenbusch  of  the  University  of 
Heidelberg,  this  hornblende  mineral  was  shown  to  be  umptekite.  The 
chemical  analysis  was  as  follows : 

Si02 62.99 

Al^Og     14.25 

Fe^Oj 2.78 

FeO 5.1s 

MgO .  1.30 

CaO 2.72 

NajO      4.86 

K2O 6.35 

HjO-t- 


H2O-    '       °-'' 

Ti02 0.16 

MnO 0.18 

100.92 
Specific  gravity,  2.732. 


Fig.    105.  — PHOTOMICROGRAPH    OF    /EGIRINE    SYENITE    FROM    GALE'S    POINT,    MANCHESTER. 
SHOWING    THE    /EGIRINE    CRYSTALS    ARRANGED    IN    A    PLANE    WITH    ORTHOCLASE. 


Fig.    106.  — PHOTOMICROGRAPH    OF    /EGIRINE    SYENITE    FROM    GALE'S   POINT,    MANCHESTER. 


UMPTEKITE    GABBRO  213 

The  rock-mass  in  which  this  umptekite  form  of  hornblende  occurs  may 
therefore  be  called  umptekite  gabbro. 

On  Salem  Neck,  near  Collins'  cove,  there  is  an  outcrop  of  umptekite  gab- 
bro, varying  from  exceedingly  coarse-  to  very  fine-grained  forms,  greatly 
differing  in  portions  of  the  same  mass  and  making  three  distinct  types. 

Microscopic  structure:  No.  i.  Orthoclase  with  fine  zonal  structure,  some 
plagioclase  with  very  coarse  twinning,  a  little  hornblende  with  inclusions  of  augite, 
much  biotite,  with  zircons  that  show  pleochroic  halos,  much  magnetite,  and  a 
few  apatite  crystals  scattered  through  the  orthoclase. 

No.  2.  Large  masses  of  brown  hornblende,  some  augite,  much  biotite  and  mag- 
netite, some  plagioclase,  a  little  orthoclase  and  apatite  and  zircons  as  inclusions  in 
the  biotite. 

No.  3.  Orthoclase  somewhat  kaolinized,  a  little  plagioclase,  hornblende,  augite, 
and  biotite.  The  augite  is  very  fresh,  and  numerous  good  basal  sections  are  seen 
in  the  field.  There  is  also  much  magnetite,  some  micro-zircons,  garnets,  and  apa- 
tite inclusions  in  the  biotite. 

Umptekite  gabbro  from  Salem  Neck  and  vicinity  in  the  nepheline 
syenite  belt  has  the  following  microscopic  structure  when  studied  in  thin 
sections  in  polarized  light.     (See  Figs.  109,  no.) 

No.  I.  Hornblende  or  umptekite  gabbro:  Numerous  well-twinned  plagioclase 
crystals,  some  orthoclase,  green  hornblende,  an  abundance  of  perfectly  fresh  biotite, 
crystals  of  olivin,  some  irregular  patches  of  quartz,  and  some  glassy  plagioclase 
as  inclusions  in  the  biotite  and  hornblende.  Some  of  the  olivin  is  inclosed  in  these 
hornblende  masses,  and  is  much  altered,  forming  magnetite.  Nvmierous  lime-iron 
garnets  and  cubical  iron  pyrites  are  also  seen  as  inclusions  in  the  plagioclase.  Crys- 
tals of  apatite  and  micro-zircons  are  abundant  in  all  parts  of  the  section.  The 
specific  gravity  of  the  plagioclase  is  2.69. 

No.  2.  Salem  Neck.  Hornblende  or  umptekite  gabbro:  Much  green  horn- 
blende, good  sections  of  augite,  some  olivin,  large  patches  of  biotite,  fine  well- 
twinned  plagioclase,  some  orthoclase,  a  little  quartz,  numerous  masses  of  quite 
large  apatite  crystals  and  a  few  zircons.  Some  of  the  olivin  is  partly  altered  to 
magnetite  and  serpentine. 

No.  3.  Salem  Neck.  Hypersthene  umptekite  gabbro:  Much  plagioclase,  some 
orthoclase,  hypersthene,  augite,  olivin,  hornblende,  biotite,  and  a  little  quartz. 
Otherwise  as  in  No.  2. 

On  the  northeastern  side  of  Woodbury's  point,  Beverly,  a  dike-like 
mass  cuts  the  pulaskite  syenite  and  Pre-Cambrian  schistose  rocks,  and  is 
principally  composed  of  umptekite  with  some  brown  hornblende,  with 
biotite  developed  on  the  edge  of  the  hornblende.  The  umptekite  occurs 
in  rectangular  to  irregular  blocks  or  large  crystal  forms  which  are  easily 


214  KERATOPHYRE 

cleavable.  Occasionally  a  piece  is  found  which  is  nearly  a  perfect  cube 
some  two  inches  square.  Usually  the  feldspars  are  in  large,  felty  masses 
of  a  bluish-white  color,  and  are  much  decomposed,  but  in  some  places 
still  showing  the  multiple-twinning  of  anorthite.  Magnetite  occurs  in 
large,  irregular  crystal  masses  surrounding  the  umptekite/ 

The  same  rock  occurs  on  the  southwest  side  of  Great  Misery  island,  and 
thin  sections  give  the  same  microscopical  character,  except  that  the  ortho- 
clase  and  plagioclase  are  much  fresher. 

Keratophyre.  —  This  formation  (see  Fig.  iii)  may  be  seen  at  low  tide 
near  the  residence  of  Mrs.  Harding  on  Boden's  point,  Marblehead  Neck. 
It  appears  as  the  much  eroded  remains  of  a  surface  flow,  and  extends  two 
htmdred  yards  in  a  northeasterly  direction,  with  a  width  of  sixty  feet  at 
the  lowest  point  of  observation.  There  are  smaller  masses  of  this  rock  three 
hundred  yards  from  this  point  in  the  same  strike  (northeast),  which  are 
exposed  only  at  extremely  low  tides.  About  five  hundred  yards  south  of 
Boden's  point  near  Flying  point,  the  eruptive  granite  cuts  the  metamor- 
phic  slate,  and  near  this  point  also  the  granite  is  cut  by  dikes  of  quartz- 
porphyry  (felsite).  Near  the  keratophyre,  and  dipping  under  it,  is  a 
banded  aporhyolite.  Both  the  granite  and  the  felsite  are  cut  by  diabase 
dikes.  The  aporhyolite  tends  to  the  northeast  and  forms  the  larger  por- 
tion of  the  bed-rock  of  the  Neck.  The  banding  of  this  aporhyolite  dips 
towards  the  harbor  nearly  north,  and  lying  upon  it  is  the  keratophyre. 
Between  the  lowest  points  of  observation  and  the  banded  aporhyolite,  a 
conglomerate  of  varying  thickness  composed  of  fine  felsitic  debris,  holding 
rounded  and  angular  fragments  of  the  aporhyolite,  is  found  in  several 
places  inclosed  in  the  keratophyre.  In  some  places  the  keratophyre  rests 
directly  upon  the  aporhyolite,  while  in  others  the  conglomerate  intervenes 
between  them.  The  line  of  contact  between  the  keratophyre  and  the 
rhyolite  debris  is  well  marked,  and  specimens  detached  at  this  point  show 
a  basal  surface  very  rough  and  pitted  where  it  conforms  to  the  irregulari- 
ties of  the  conglomerate.  The  rock  is  much  decomposed  on  the  surface, 
but  the  least  altered  specimens  obtained  are  of  a  brownish  or  bluish-gray 
color,  having  a  conchoidal  fracture  and  a  compact  ground-mass,  holding, 
occasionally,  large,  glassy  crystals  of  anorthoclase,  some  of  which  are  one- 
fourth  of  an  inch  in  length,  and,  rarely,  plates  of  biotite. 

Microscopical  analysis  shows  the  ground-mass  to  be  filled  with  lath- 
shaped  feldspar  crystals,  which  are  somewhat  decomposed.  The  base  is 
an  earthy  kaolinized  mass,  with  irregular  masses  of  quartz  and  earthy 
'  Min.  Pet.  Mitth.,  Vol.  XIX,  p.  368. 


Fig.   10  7.  — SALEMITE    OUTCROP    (IN    THE    FOREGROUND)    AND    LEDGE    OF    UMPTEKITE    GABBRO 
(BEYOND   THE    PATH),    SALEM    NECK. 


Fig.  10  8.  — UMPTEKITE  GABBRO   CUT   BY    VEINS   OF    PULASKITE   SYENITE,    SALEM    NECK. 


KERATOPHYRE 


217 


limonite.  The  phenocrysts  occur  as  crystals  with  a  square  cross-section, 
owing  to  the  presence  of  the  base  and  brachypinacoid ;  in  addition  to  the 
two  cleavages,  there  is  a  rough  transverse  Assuring.  The  crystals  are 
quite  glassy  when  fresh.  The  different  feldspar  sections  show  marked 
optical  peculiarities ;  there  is  often  a  very  fine  single-  or  double-twinning 
(microcline) ;  sometimes  the  whole  of  one  section  of  the  mineral  consists  of 
irregular  areas  not  extinguishing  in  common,  which  resemble  the  phenom- 
ena produced  by  mechanical  causes.  These  areas  contain  very  fine  lines 
crossing  each  other  at  various  angles  in  the  different  areas;  in  other  cases 
there  is  a  very  fine  zonal  structure.  Sections  prepared  parallel  to  the  base 
show  this  fine,  irregular  double-twinning,  and  give  an  extinction  i°  to  2° 
oblique  to  the  line  of  the  second  cleavage  (  00  P'SS) ;  and  sections  parallel  to 
the  latter  cleavage  give  an  extinction  about  9°  oblique  to  the  line  of  the 
first  cleavage,  with  an  obtuse  positive  bisectrix  about  perpendicular  to 
the  face,  the  acute  bisectrix  making  an  angle  of  9°  with  the  basal  cleavage. 
These  sections  sometimes  show  a  very  fine,  indistinct  microperthite 
striation.  The  angle  between  the  two  cleavages  was  determined  in  the 
reflecting  goniometer  as  approximately  89°  42',  about  that  of  microcline. 
The  specific  gravity  of  fragments  determined  by  Westphal  balance  and 
Thoulet  solution  was  between  2.570  and  2.572. 

The  following  analyses  of  the  feldspar  (I.)  and  the  rock  (II.)  were 
made  in  the  laboratory  of  the  United  States  Geological  Survey  at  Wash- 
ington by  Dr.  Thomas  Chatard. 


Feldspar. 

HgO  at  110°  C .04 

H3O  at  red  heat .37 

Sibj 65.66 

TiO/      

P^O, 

AI2O3      20.0s 


FeO 
MnO 
CaO 
MgO  , 
K^O    . 
Na,0 


traces 
traces 

•13 
.67 
18 


56 


II. 

Keratophyre. 

.91 
1.28 


70 


The  Ti02  was  not   very  pure,   and  its  presence  is  not  absolutely  certain 


218  KERATOPHYRE 

III.  IV. 

Gmelin,  No.  I.  Gmelin,  No.  2. 

SiOj 65.90  65.19 

AljOj      19-46  19. 99 

Fefi, 44  .63 

CaO 28  .48 

MgO 

K2O 6.55  7.03 

NajO      6.14  7.08 

HjO 12  .34 

Specific  gravity,  2.587. 

It  is  evident  from  the  analyses  and  optical  properties  that  this  is  a 
triclinia  soda-potash  feldspar  of  remarkable  purity,  with  very  evenly  bal- 
anced percentages  of  Na  and  K,  belonging  to  the  anorthoclase  group  of 
Rosenbusch.  For  comparison,  are  appended  analyses  (III.  and  IV.)  by 
Gmelin,  of  anorthoclase  from  the  augite  syenite  of  Norway  (Brogger,  "  Die 
Sil.  Etagen  2  und  3,"  etc.,  p.  261).  In  the  rock  as  a  whole,  the  same 
even  balance  between  Na  and  K  is  noticeable,  and  the  insignificant  quan- 
tity of  lime  and  magnesia.  Allowing  for  the  free  quartz,  base  and  de- 
composition products  as  causing  a  relative  increase  of  silica  and  iron  and 
decrease  of  the  alumina  and  alkalies,  it  is  evident  that  the  feldspars  of  the 
ground-mass  are  closely  allied  chemically  to  the  porphyritic  crystals,  and 
are  probably  also  anorthoclase.  The  rock  is  therefore  a  very  pure  type 
of  keratophyre. 

The  microscopical  structure  of  the  sections  made  is  as  follows : 

No,  I.  Keratophyre  with  anorthoclase  crystal  cut  obliquely  to  an  optic  axis. 
Ground-mass  made  up  of  minute  twinned  lathshaped  crystals  of  feldspar,  some- 
what kaolinized,  some  quartz,  and  an  earthy  fibrous  kaolinized  base.  In  the  center 
of  the  porphyritic  feldspar  crystal  are  numerous  microliths  and  a  few  ferritic  masses, 
similar  to  and  probably  composed  of  the  base,  which  penetrates  the  edges  of  the 
crystal. 

No.  2.  Keratophyre  and  an  aggregate  of  the  porphyritic  crystals.  Ground- 
mass  nearly  as  in  No.  i.  One  of  the  phenocrysts  shows  twinning  after  the  Carls- 
bad type. 

No.  3.  Keratophyre  with  one  porphyritically  inclosed  crystal  (see  Fig.  113). 
The  crystal  is  cut  nearly  parallel  to  the  second  cleavage,  and  gives  an  almost  per- 
fect interference  figure  of  the  positive  bisectrix.  The  basal  cleavage  is  well  devel- 
oped, and  the  striae,  or  fine  twinning,  are  well  marked  in  polarized  light.  The 
ground-mass  is  more  generally  composed  of  the  minute  lath-shaped  feldspar  crystals, 
some  of  which  are  clearly  twinned  anorthoclase  of  the  same  form  as  the  larger  crys- 
tals.    There  are  also  small  patches  of  quartz. 

No.  4.    Keratophyre  with  one  large  porphyritic  feldspar  crystal  cut  obliquely  to 


Fig.  10  9.— PHOTOMICROGRAPH    OF    HORNBLENDE    UMPTEKITE   GABBRO    FROM    SALEM    NECK. 


Fig.  I  10.  — PHOTOMICROGRAPH    OF    UMPTEKITE   GABBRO    FROM    EASTERN    SIDE   OF    MISERY    ISLAND. 


KERATOPHYRE  221 

the  brachydiagonal  (see  Fig.  114),  which  in  polarized  light  shows  a  microperthitic 
intergrowth  and  a  very  perfect  example  of  fine  and  interrupted  twinning.  Through 
the  crystal  are  several  fluid  cavities  and  a  few  microliths  of  a  reddish  color.  The 
ground-mass  is  more  kaolinized,  and  the  minute  lath-shaped  crystals  are  less  distinct. 
Small,  irregular  masses  of  quartz  and  considerable  limonite  and  earthy  matter  per- 
vade this  section. 

No.  5.  Keratophyre  section  cut  across  a  joint  plane  which  is  filled  with  vein 
quartz  :  numerous  irregular  patches  of  quartz  are  scattered  all  through  the  section. 
One  mass  is  a  basal  section  of  original  (?)  quartz;  it  gives  the  uniaxial  cross,  and  is 
shown  to  be  positive  by  the  mica  plate.  Some  scales  of  biotite  and  numerous 
small  grains  of  magnetite  are  seen  in  the  ground-mass,  which  is  composed  of  a  fib- 
rous, feebly  polarizing  kaolinized  mass  of  the  decomposed  minute  lath-shaped  feld- 
spar crystals.  One  of  the  inclosed  phenocrysts  cut  nearly  parallel  to  the  base 
shows  numerous  microlithic  inclusions,  and  several  fluid  cavities  in  which  the  bubble 
movement  is  seen.     The  outer  edge  is  deeply  penetrated  by  the  ground -mass. 

The  occurrence  of  this  keratophyre  as  a  surface  flow,  in  close  proximity 
to  the  large  intrusive  masses  of  nepheline  syenite,  pulaskite  syenite  and 
Essexite  of  Salem  Neck  and  the  islands  in  Salem  harbor,  and  the  augite 
syenite  of  Marblehead  and  the  Beverly  shore,  is  interesting,  as  showing 
the  various  forms  assumed  here  by  the  alkaline  magmas  under  different 
geological  conditions  or  at  different  periods. 


CHAPTER  VIII 

IGNEOUS  VOLCANIC  ROCKS 

These  rocks  are  easily  separated  into  two  great  groups,  the  acid  and 
the  basic  volcanics.  The  acid  volcanics  occur  in  massive  forms.  Expo- 
sures may  be  seen  on  Marblehead  Neck,  at  Swampscott,  Lynn,  and  Saugus, 
and  from  there  extending  into  Middlesex  County.  (See  Figs.  115,  116.) 
These  rocks  also  extend  easterly  into  the  bay  by  islands  and  ledges. 
Another  area  appears  at  Rowley  and  Newbury  in  the  form  of  a  long  and 
comparatively  narrow  mass  not  over  one  mile  in  width,  extending  in  a 
northeasterly  direction  from  Batchelder's  brook,  at  Clay  lane,  Rowley, 
across  Rowley  and  Newbury  to  the  tidal  marsh  beyond  Pine  island. 

The  acid  volcanics  are  tufaceous,  fragmental,  and  massive,  and  the 
exposures  are  more  extended  in  area  than  the  basic  volcanics.  The  mas- 
sive eifusives  often  possess  a  compact  cryptocrystalline  felsitic  texture,  and 
on  weathered  surfaces  are  seen  as  banded  structures  with  light  and  red 
to  gray  tints  which  conspicuously  reveal  curving  and  crumpled  lines  of 
flow  movement.  This  fluxion  banding,  if  the  rock  is  much  weathered,  is 
accompanied  by  an  easy  cleavage  into  slabs  parallel  to  the  fluxion  planes. 
A  good  example  may  be  observed  at  Boden's  point,  Marblehead  Neck- 
Below  high-water  mark,  in  the  harbor  off  Boden's  point,  occurs  a  coarse 
breccia  or  aporhyolite  tuff,  which  is  covered  by  a  sheet  of  lava  rock,  kera- 
tophyre,  composed  of  anorthoclase  feldspars.  The  keratophyre  at  this 
point  is  only  exposed  below  high-water  mark.  It  also  appears  on  a  ledge 
east  of  the  Eastern  Yacht  Club's  pier.  On  Marblehead  rock,  weathered 
surfaces  of  these  banded  forms  of  volcanic  rocks  are  conspicuously  seen. 
(See  Fig.  112.)  Amygdaloidal  types  of  the  basic  volcanics  occur  in  Row- 
ley on  the  northern  side  of  Clay  lane,  near  the  Dummer  Academy  grounds, 
and  may  be  traced  for  nearly  two  hundred  yards  on  the  summit  of  the 
ridge.  These  amygdules  are  round,  and  of  a  red  color  merging  into  lighter 
shades.  In  cross  section,  they  are  seen  to  be  composed  of  a  fine  radiating 
structure  with  an  open  center.  In  some  instances  the  centers  are  much 
lighter  in  color.  A  partial  analysis  by  Mrs.  E.  H.  Richards,  of  the  Massa- 
chusetts Institute  of  Technology,  shows  a  composition  of  about  one  half 


Fig.  I  I  I.  — KERATOPHYRE    FROM    THE    HARBOR    SIDE    OF    MARBLEHEAD    NECK. 
Anorthoclase  crystals  appear  as  white  spots.     Size  of  block  6x10  inches. 


Fig.  112.  -FOLIATED    APORHYOLITE    FROM    A    BARE    LEDGE    OFF    IVIARBLEHEAD    NECK,    SHOWING 
WEATHERED    SURFACE. 


IGNEOUS    VOLCANIC    ROCKS  225 

silica.  They  are  forms  of  spherulites  and  vary  in  size  from  a  small  pea  to 
a  half  inch  in  diameter. 

At  Kent's  island,  Newbury,  these  rocks  are  found  in  great  variety. 
One  large  mass  occupies  the  greater  part  of  the  center  of  the  island  and  is 
so  much  decomposed  that  it  is  nearly  kaolin.  An  area  on  the  west 
side  of  the  island  has  a  deposit  which  is  fine  and  white  as  chalk  and  is 
an  excellent  pottery  clay. 

Fliixion-banded  basic  forms  are  found  on  Eagle  hill,  Kent's  island. 
The  rock  is  vesicular  on  the  bank  of  Parker  river  and  at  the  extreme  eastern 
part  of  the  island,  but  it  is  epidotic  on  the  summit  of  the  hill.  Previous 
to  the  intrusion  of  these  volcanics,  the  original  bed-rocks  of  the  island  were 
slates  and  sandstones  cut  by  a  mass  of  quartz  hornblende  diorite  which 
is  now  cut  and  brecciated  by  the  aporhyolites,  while  the  sedimentary  beds 
are  calcined  and  so  greatly  metamorphosed  that  in  places  they  are  hardly 
recognizable.  At  the  contact  of  the  volcanics  and  the  diorite  mass,  on 
the  southern  part  of  the  island,  the  rocks  are  well  mineralized  with  zinc, 
copper,  iron,  and  galena.  During  the  mining  excitement  in  1875,  a  shaft 
was  sunk  at  this  point.  On  the  southeastern  part  of  the  island,  by  the 
side  of  the  railroad  track,  there  is  an  exposure  of  a  conglomerate  in  which 
nearly  all  of  the  fragments  are  angular,  and  not  only  comprise  volcanics 
but  also  fragments  of  diorite  and  sandstone.  Thin  sections  of  the  volcan- 
ics from  Pine  island,  Newbury,  show  trichites  in  a  glassy  ground-mass. 
South  of  Parker  river,  in  Rowley,  is  a  spherulite  rock  commonly  called 
toadstone.  It  is  a  volcanic  form  in  a  long  tongue  or  dike  extending  from 
the  mass  north  of  the  river  and  here  cutting  the  diorite  which  is  in  turn 
cut  by  an  olivin  basalt  dike.  This  dike  has  calcined  the  spherulitic  rock 
so  that  the  spherulites  are  of  a  reddish  color  merging  into  black  and 
giving  a  distinct  form  to  the  rock  near  its  contact  with  the  dike. 

At  Marblehead  Neck  and  on  High  rock,  Lynn,  narrow  dikes  of  quartz 
porphyry,  a  later  formation  of  the  volcanic  series,  cut  through  all  the 
other  numbers  of  these  rocks,  showing  them  to  belong  to  a  later  period.  A 
fine  example  raay  be  seen  at  the  first  outcrop  on  approaching  Marblehead 
Neck,  and  another  exposure,  cutting  across  the  Neck  to  the  ocean,  appears 
by  the  side  of  the  lane  which  leads  from  Tucker's  landing  to  the  Main 
street  on  the  Neck.  South  of  the  lighthouse  this  rock  is  extremely  hard. 
It  has  the  characteristic  conchoidal  fracture  with  a  very  perfect  jointing, 
and  is  fotmd  in  blocks  two  or  three  inches  wide  and  equally  thick  and 
suggesting,  in  appearance,  tiles  in  regular  layers.  Cat  island  and  Lowell 
island  are  largely  agglomerate  with  several  distinct  forms,  both  coarse  and 


226  IGNEOUS    VOLCANIC   ROCKS 

fine,  and  green  and  darker  colored.  Satan  rock  is  a  brick-red  spherulitic 
aporhyolite  with  a  glassy  base.  The  Gooseberry  islands  are  a  conglom- 
erate aporhyolite,  and  Halfway  rock  is  a  mass  of  coarse  porphyritic  apor- 
hyolite containing  numerous  lithophase  forms.  These  delicate  shell-like 
structures  are  identical  in  form  with  those  taken  from  the  obsidian  cliffs  in 
the  Yellowstone  and  figured  in  the  Seventh  Annual  Report  of  the  United 
States  Geological  Survey,  pages  264-265. 

A  quartz  porphyry  volcanic  dike  at  Marblehead  which  cuts  hornblende 
diorite,  has  ntimerous  fine  examples  of  quartz  phenocrysts  surroimded  with 
spherulites.  This  rock  is  a  liparite.  (See  Fig.  117.)  East  of  Boden's 
point,  on  the  harbor  side,  the  banded-fltixion  rock  (see  Figs.  118,  119, 
120),  is  succeeded  by  a  massive  porphyritic  form  of  the  basic  series  which 
contains  veins  of  epidote.  This  is  joined  to  a  coarse  breccia,  the  bed 
upon  which  the  flow  of  keratophyre  rests.  Northeast  of  Sparhawk 
beach,  the  high  bluff  is  composed  of  a  purplish  feldspar  porphyritic  apor- 
hyolite which  assumes  a  fluid  structure  near  the  Point  and  contains 
numerous  concretionary  formations,  varying  in  size  from  a  small  pea  to  a 
diameter  of  two  feet.  (See  Fig.  121.)  Some  are  flattened  as  if  after  having 
been  ejected  into  the  air  they  had  fallen  back  into  the  viscid  lava. 

The  primary  constituents  which  have  been  preserved  in  these  volcanics 
are  the  alkaH  feldspars,  quartz,  and  magnetite.  Lime-magnesian  and 
ferro-magnesian  minerals  are  only  found  at  or  near  a  contact  with  some 
basic  dike  or  in  the  agglomerate  series.  On  Lowell  island,  glaucophane 
is  usually  present.  Feldspars  occur  both  as  scattered  phenocrysts  and  as 
components  of  the  grotmd-mass,  assuming  granular  forms  in  lath-shaped 
crystals,  and  radiating  fibers.  The  lath-shaped  feldspars  are  usually  mi- 
croperthitic.  The  extinction  indicates  that  albite,  orthoclase,  and  anor- 
thoclase  are  present.  Quartz  occurs  in  the  form  of  phenocrysts  and  also 
as  a  constituent  of  the  ground-mass.  The  textures  found  in  these  lavas 
are  the  granular  trachytic  porphyritic  fluxion,  spherulitic,  perlitic,  and 
amygdaloidal. 

By  megascopic  examination,  hand  specimens  exhibit  as  great  a  range  of 
color  as  of  texture.  Light-green  to  dark  grass-green  shades  occur  and  gray 
with  various  shades  of  pink  and  purple  and  also  a  brick-red.  The  frag- 
mental  materials,  such  as  the  breccias  and  agglomerates,  are  readily  recog- 
nized by  the  weathered  surfaces,  which  owe  their  character  to  the  vari- 
ously colored  fragments  contained  in  a  light-green  or  pink  base.  Red 
hematite  is  disseminated  through  the  feldspathic  mineral  as  a  microscopic 
dust  and  produces  the  various  shades  of  red  and  pink.     The  green  colors 


-PHOTOMICROGRAPH    OF   AN    ANORTHOCLASE    CRYSTAL    IN    KERATOPHYRE    FROM 
MARBLEHEAD    NECK. 


fig.  I  14. —  PHOTOMICROGRAPH    OF   AN    ANORTHOCLASE    CRYSTAL    IN    KERATOPHYRE    FROM 
MARBLEHEAD    NECK. 


IGNEOUS   VOLCANIC  ROCKS  229 

are  due  to  pyrite  and  epidote,  derived  from  the  alteration  of  the  feldspa- 
thic  ground-mass. 

In  this  area,  the  age  of  these  volcanics  is  somewhat  problematical. 
As  veins  and  masses  are  erupted  into  the  Cambrian  sedimentary  rocks  at 
Saugus  and  Lynn,  and  especially  at  Kent's  island,  undoubtedly  they  are 
Post-Cambrian.  They  are  also  younger  than  the  hornblende  granite,  for 
on  Marblehead  Neck  they  cut  through  and  inclose  masses  of  these  granites 
which  are  younger  than  the  diorites.  Hornblende  diorite  is  cut  by  a 
spherulitic  aporhyolite  liparite  dike  at  Throgmorton's  cove,  Marblehead. 

The  agglomerates  on  Lowell  island  and  Cat  island  are  rhyolitic  tufas, 
the  microscopical  structure  showing  them  to  be  composed  of  sharp-edged 
fragments  of  the  aporhyolites  and  volcanic  glass  embedded  in  a  ground- 
mass  of  ashy  materials.  Much  of  the  glass  has  been  altered  to  quartz 
and  the  ash  to  an  earthy  chloritic  mass.  Some  magnetite  appears  and 
also  spherulites  and  skeleton-crystals  of  augite.  In  places  the  fluxion 
of  the  micro-felsitic  ground-mass  shows  secondary  quartz  in  radiating 
fibrous  lines. 

North  Gooseberry  island  is  a  large  mass  of  porphyritic  aporhyolite  con- 
taining considerable  amounts  of  original  glass,  and  a  conglomerate  apor- 
hyolite in  which  the  pebbles  are  weathered  out  very  conspicuously.  (See 
Fig.  12  2.)  Some  of  the  well-rounded  pebbles  are  from  one  to  three  inches 
in  diameter.  The  fine-grained  flow  has  a  perlitic  structure  and  contains 
much  original  glass,  in  twisted  and  curved  forms. 

At  the  northeastern  end  of  Thatcher's  island  there  is  a  wide,  dike-like 
mass  occupying  at  least  a  third  of  the  area  of  the  island,  which  seems  to 
be  a  spherulitic  quartz  porphyry.  A  microscopical  examination  of  thin 
sections  of  this  rock  shows  it  to  be  composed  of  quartz  phenocrysts,  with 
phenocrysts  of  orthoclase  perthite,  having  albite  intergrowths  across  the 
crystals.  Glaucophane,  biotite,  and  magnetite  are  present;  also  a  felsitic 
ground-mass  in  which  is  considerable  quartz  containing  original  glass 
and  numerous  fluid  cavities.  In  the  ground-mass  are  rutile  crystals  with 
prisms  joined  at  right  angles  with  each  other.  Macroscopically  this  dike 
resembles  the  paisanite  at  Magnolia,^  and  in  the  cove  between  Wood- 
bury's point  and  Hospital  point,  Beverly. 

'  Journal  of  Geology,  Vol.  VII,  pp.  111-113. 


CHAPTER   IX 

THE    MINERALS    OF    ESSEX    COUNTY 

The  following  list  of  the  minerals  of  Essex  County  has  been  prepared 
after  a  careful  examination  of  the  work  of  the  earlier  mineralogists,  and 
diligent  search  in  almost  every  portion  of  the  County  for  species  not  pre- 
viously noticed.  Doubtless  it  is  not  absolutely  complete.  In  studying 
the  rock  formations,  more  than  sixteen  htmdred  thin  sections  have  been 
made  for  microscopical  study.  Of  the  minerals  enumerated  nearly  all 
are  represented  by  excellent  specimens  in  the  Cotmty  collection  in  the 
museum  of  the  Peabody  Academy  of  Science  at  Salem.  In  connection 
with  the  minerals  will  be  found  collections  illustrating  the  rocks  of  the 
County  and  the  geological  formations,  including  photographs  of  the  more 
interesting  features.  The  rocks  from  which  these  minerals  -were  taken 
represent  twenty-nine  distinct  rock-formations,  and  several  thousand 
outcropping  ledges,  the  greater  nimiber  of  which  have  never  been  broken 
into  except  to  collect  the  few  specimens  required  to  determine  the  char- 
acter of  the  rock.  As  these  ledges  are  worked  into  and  studied  they  will, 
without  doubt,  furnish  many  mineral  species  new  to  the  County,  and  an 
extremely  interesting  field  is  open  to  the  mineralogist.  The  arrange- 
ment of  the  minerals  in  this  list  follows  the  text  book  of  Prof.  E.  S.  Dana, 
the  tenth  revised  edition. 

Gold.  The  gray  copper,  galena,  and  quartz,  from  the  Chipman  silver 
mine  at  Newbury,  contain  gold,  and  gold  has  been  reported  from  various 
other  mines  in  the  neighborhood,  and  also  from  Boxford,  Topsfield,  Lynn- 
field  Centre,  and  Saugus.  The  analysis  of  the  gray  copper  from  the  Chip- 
man  mine  made  by  Prof.  R.  H.  Richards  of  the  Massachusetts  Institute 
of  Technology,'  gives:  silver,  $1,422.00  per  ton;  gold,  $145.12  per  ton  and 
27  per  cent  of  copper.  The  galena  (30  pounds)  from  the  Chipman  mine 
analyzed  by  Professor  Richards,  yielded  25  lbs.  of  refined  lead,  436.32  grains 
of  silver  and  4.19  grains  of  gold.  An  analysis  of  this  galena  made  by  the 
author  at  the  Lawrence  Scientific  School  gave  silver  at  the  rate  of  27 
ounces  per  ton.     The  gray  copper  of  the  quality  above  indicated  is  very 

'  Proceedings,  Boston  Society  of  Natural  History,  Vol.  XVII,  pp.  200-204. 

230 


Fig.  I  I  5.  — CASTLE    HILL,    SAUGUS,    A    MASSIVE    OUTCROP    OF    APORHYOLITE. 
An   ancient  volcanic  rock. 


Fig.   116.  — CASTLE    HILL,    SAUGUS. 


THE    MINERALS    OF    ESSEX    COUNTY  233 

rare  even  in  Newbury,  and  it  is  doubtful  if  it  is  to  be  found  in  the  County 
in  sufficient  quantities  to  be  mined  at  a  profit. 

Graphite.  This  occurs  in  minute  foliated  scales  in  the  granitic  rocks 
of  Peabody  and  Danvers,  and  in  the  slaty,  carboniferous  shales  of  Tops- 
field,  Middleton,  and  Lynnfield  Centre. 

Stibnite:  Gray  Antimony.  Found  associated  with  galena  at  the 
Newbury  and  Newburyport  silver  mines. 

Molybdenite.  Found  in  foliated  masses  of  considerable  size  at  the 
Pomeroy  granite  quarry  at  Gloucester,  in  the  augite  syenite  at  Salem 
Neck,  and  some  good  specimens  have  been  found  in  the  diorite  at  Marblehead. 

Silver  Ore.  At  Newbury,  Newburyport,  Amesbury,  Rowley,  Box- 
ford,  and  Lynnfield  Centre. 

Galena:  Lead  Ore.     Found  in  the  places  last  named. 

Bornite  :  .Variegated  Copper  Ore.  At  the  Luther  Noyes  copper  mine 
and  the  southern  part  of  Kent's  island,  Newbury. 

Chalcopyrites  :  Copper  Pyrites.  Found  at  the  Luther  Noyes  copper 
mine,  the  Chipman  silver  mine,  and  at  Kent's  island,  Newbury,  the 
Stephen  Osgood  mine  in  South  Georgetown,  and  the  old  Governor  Endi- 
cott  copper  mine  in  Topsfield. 

Sphalerite:  Zinc  Blende.  This  occurs  in  considerable  masses  at  all 
of  the  mines  in  Newbury,  Newburyport,  and  Rowley  and  also  in  much 
larger  quantities  in  the  John  Pettingill  mine  at  Amesbury. 

Pyrrhotite  :  Nickel  Ore.  From  the  Luther  Noyes  nickel  mine  in 
Newbury,  and  in  a  small  vein  exposed  in  the  augite  syenite  at  Poorhouse 
hill  in  Beverly. 

Pyrite:  Iron  Pyrites.  This  occurs  in  large  masses  near  the  Harri- 
man  mine  at  Boxford,  and  in  Newbury  in  connection  with  the  galena 
and  silver  ores.  It  is  also  common  in  small  quantities  in  nearly  all  of 
the  bed-rocks  of  the  County. 

Marcasite  :  White  Iron  Pyrites.  Found  in  large  masses  at  the  Luther 
Noyes  nickel  mine,  Newbury. 

ArsenopyriTe  :  Mispickle.  This  occurs  in  thin  sheets  or  veins  at  the 
John  Pettingill  mine,  Amesbury,  and  good  specimens  were  found  at  an 
old  mine  near  the  Parker  river,  Rowley. 

Tetrahedrite  :  Gray  Copper.  Good  specimens  of  this  mineral  were 
found  in  the  dump  heaps  of  the  Chipman  silver  mine,  Newbury,  and  at 
the  Stephen  Osgood  mine.  South  Georgetown. 

Halite:  Salt.  Found  as  incrustations  and  in  acicular  crystals  on 
rocks  and  the  borders  of  tide  pools  at  the  sea-shore. 


234  THE    MINERALS    OF    ESSEX    COUNTY 

Fluorite:  Fluor-spar.  In  irregular,  crystalline  masses  in  the  grani- 
tite  at  the  quarry  of  the  Rockport  Granite  Co.,  Rockport,  and  also  asso- 
ciated with  galena  at  Lynnfield  Centre. 

Hematite  :  Specular  Iron.  Found  on  the  surfaces  of  the  slickensides 
of  diorite  at  Salem,  in  amphibolite  at  Putnamville,  and  in  hornblende 
granites  at  Peabody. 

Hematite,  var.  Micaceous  Hematite.  Found  in  the  bed-rock  of  the 
Tophet  hill  lost  gold  mine,  Lynnfield  Centre. 

Hematite,  var.  Red  Ochre.  At  Beverly  Cove,  Danvers,  Topsfield, 
etc.     This  is  the  common  anhydrous  form. 

Menaccanite  :  Ilmenite :  Titanic  Iron.  Seen  in  microscopic  patches 
in  nearly  all  of  the  eruptive  rocks,  especially  in  the  augite  syenites,  dio- 
rites,  and  mica-schists. 

Leucoxene.  This  mineral,  a  decomposition  product  of  the  titanite,  is 
usually  seen  surrounding  the  titanite  or  entirely  replacing  it. 

Magnetite  ;  Iron.  This  occurs  in  masses  in  the  elceolite  zircon  syenite 
at  Great  Haste  ledge,  Salem  harbor,  and  is  common  in  crystals  and  small 
grains  in  all  of  the  eruptive  rocks  of  the  County. 

Chromite  ;  Chromic  Iron.  In  octahedral  crystals  in  the  limestone  and 
serpentine  at  the  Devil's  basin,  Newbury. 

Rutile.  Common  in  microscopic  crystals  in  the  metamorphic  Cam- 
brian rocks  in  all  parts  of  the  County.  Larger  crystals  occur  in  the  granites 
at  Swampscott,  West  Wenham,  etc. 

Turgite:  Red  Ochre.  An  earthy  form  of  this  mineral  occurs  in  a 
hillside,  northwest  of  the  old  meeting-house,  at  Beverly  Farms. 

Limonite:  Brown  Hematite:  Bog  Iron  Ore.  Found  in  the  beds  of 
brooks  and  small  ponds  in  nearly  all  of  the  towns  in  Essex  County.  This 
was  the  ore  used  at  the  Saugus  Iron  Works,  in  1643,  the  first  iron-casting 
works  in  America. 

Limonite:  Brown  Ochre.     At  the  mineral  paint  mine,  Georgetown. 

Limonite  :  Yellow  Ochre.     At  Danvers,  Topsfield,  Newbury,  etc. 

Limonite  :  Clay  Iron  Stone.  Good  specimens  of  this  mineral  are 
found  in  pockets  in  the  granite  at  the  Pomeroy  quarry,  Gloucester. 

Xanthosiderite.  Found  in  segregated  masses,  stalactitic  and  bot- 
ryoidal  in  form,  in  crevices  of  the  granite  at  the  quarry  of  the  Rockport 
Granite  Co.,  Rockport. 

Brucite.  a  mineral  belonging  to  the  magnesia  group,  found  asso- 
ciated with  serpentine  at  the  serpentine  ledge,  Lynnfield  Centre. 

Wad  :  Bog  Manganese.     Found  in  large  masses  in  a  meadow  and  brook 


Fig.   I  17.— PHOTOMICROGRAPH    OF    LIPARITE. 
A  quartz  porphyry  aporhyolite  with  spherulites. 


Fig.   I  18.  — APORHYOLITE    OUTCROP    ON    THE    HARBOR    SIDE    OF    MARBLEHEAD    NECK,    SHOWING    THE 
FLOW   OF    THE    LAVA. 


THE    MINERALS    OF    ESSEX    COUNTY  237 

at  Putnamville,  and  in  the  form  of  rotinded  concretions  in  small   ponds 
and  spring-holes  at  Peabody  and  Topsfield. 

Quartz.     Massive   vein   quartz   occurs   at    North    Beverly,    Danvers, 
and  various  other  places  in  the  County. 

Quartz:  Rock  Crystal.  Found  in  large  masses  and  crystals  in  peg- 
matite veins  at  Andover,  Nahant,  Rockport,  etc., 

Quartz  :  Drusy  Quartz.  In  minute  crystals  at  Danvers,  Nahant,  and 
West  Newbury. 

Quartz:  False  Topaz.     Light  Yellow  color,  Rockport. 

Quartz  :  Smoky  Quartz.  The  massive  vein  form  is  found  in  the  rhyo- 
lites  of  Marblehead  and  in  the  granite  of  Gloucester  and  Rockport. 

Quartz:  Cairngorm  Stone.  Found  in  nearly  black  crystals  at  the 
Pomeroy  quarry,  Gloucester,  and  at  Rockport. 

Quartz:  Milky  Quartz.  Massive  veins  occur  at  South  Georgetown 
and  Groveland. 

Quartz  :  Ferruginous  Quartz.    In  the  carboniferous  slates  of  Topsfield. 

Quartz  :  Rose  Quartz.     Occasionally  found  in  the  glacial  drift. 

Prase  :  Actinolitic  Quartz.     A  vein  occurs  at  Bass  Point,  Nahant. 

Chalcedony.  Good  specimens  occur  at  Prospect  Hill,  Beverly,  and  it  is 
also  foiuid  filling  the  amygdules  of  the  amygdaloidal  melaphyre  at  Saugus. 

Basanite  :  Chert.  Found  in  the  Cambrian  rocks  at  Peabody,  Mid- 
dleton,  Rowley,  and  Nahant  head,  Nahant. 

Jaspelite.  At  Saugus  Centre  and  Nahant.  This  is  the  so-called  red 
jasper  as  popularly  known. 

QuARTZiTE.  At  Saugus,  Lynnfield  Centre,  etc.,  forming  large  beds  in 
the  lower  Cambrian  rock-mass. 

Opal,  var.  Silicious  Sinter.  Found  as  segregated,  granular,  stalactitic 
masses  at  the  contact  of  the  augite  syenite  and  granite  in  Beverly. 

Opal,  var.  Tripolite:  Infusorial  Earth.  Found  in  beds  of  brooks  and 
meadows  in  Danvers.  At  "West  Boxford,  beds  occur  two  feet  or  more 
in  thickness. 

Hypersthene.  In  irregular,  cleavable,  crystalline  grains  and  masses 
in  the  hypersthene  gabbro  at  Misery  island  and  Salem  Neck. 

Wollastonite  :  Tabular  Spar.  A  bladed  variety  of  this  mineral  is 
found  at  the  Devil's  den,  Newbury. 

DiALLAGE.  Found  in  large  crystalline  masses  at  the  Luther  Noyes 
nickel  mine,  Newbury. 

Pyroxene,  var.  Augite.  In  irregular  crystals  in  the  augite  nepheline 
syenite  at  Salem  Neck,  Beverly,  and  Manchester. 


238  THE    MINERALS    OF    ESSEX    COUNTY 

DiOPSiDE,  var.  Brown  Augite.  This  occurs  as  irregular,  microscopic 
crystals  in  the  augite  nepheline  syenite  on  the  Pickman  estate,  Beverly 
Cove. 

AcMiTE.  This  occurs  as  small  acicular  crystals  in  the  augite  syenite 
at  Powder  House  hill  in  Essex,  and  at  Lanesville  in  Gloucester. 

.^Egirine.  Typical  bent  crystals,  sometimes  three  inches  long,  are 
foimd  in  the  EEgirine  syenite  at  Gale's  point,  Manchester.  It  is  also  seen 
in  thin  sections  of  the  elaeolite  zircon  syenite  of  Salem  Neck  and  Beverly, 
when  studied  with  the  microscope. 

Enstatite.     In  micro-crystals  in  the  olivin  gabbro  of  Salem  Neck. 

Bronzite.  Pound  with  the  enstatite  on  Salem  Neck,  and  also  in  a 
coarse  pegmatitic  mass  on  Misery  island,  Salem  Harbor. 

Hornblende.  Irregular  crystals  are  abundant  in  the  hornblende 
granite  of  Peabody  and,  microscopically,  it  is  common  in  the  diorite, 
syenites,  and  the  dike  rocks. 

Tremolite.     At  the  Devil's  basin,  Newbury. 

AcTiNOLiTE.  Long  crystals  are  found  at  Bass  Point,  Nahant,  and 
it  is  also  found  in  a  large  pegmatite  boss  in  the  quarry  of  the  Rockport 
Granite  Co.,  Rockport. 

AsBESTUS,  pseudomorph  of  Actinolite.  A  vein  six  inches  wide,  in 
the  diabasic  norite,  occurs  at  Bass  Point,  Nahant. 

Arfvedsonite  :  Alkali  Hornblende.  Irregular  crystals  are  found  at 
Salem  Neck,  and  larger  masses  in  the  elasolite  zircon  syenite  on  Coney 
island,  Salem  harbor. 

AiNiGMATiTE.  Rare,  but  found  in  microscopic  masses  in  the  elaeo- 
lite zircon  syenite.  Great  Haste  ledge,  Salem  harbor. 

Cossyrite.     In  microscopic  crystals  in  the  augite  syenite  at  Magnolia. 

Glaucophane.  a  deep  blue  hornblende.  In  massive  forms  in  the 
augite  hornblende  granite  at  Pickering's  point,  Salem,  and  in  the  granite 
porphyrite  at  Marblehead  Neck,  etc. 

Chrysolite:  Olivin.  Found  in  porphyritic  crystals  in  olivin  basalt 
dike  rocks,  Salem  Neck,  etc. 

Fayalite.  a  large  mass,  at  a  depth  of  sixty  feet,  occurs  in  the  quarry 
of  the  Rockport  Granite  Co.,  Rockport. 

Danalite.  In  irregular  masses  and  microscopic  blebs  scattered 
through  the  hornblende  biotite  granite  at  the  quarry  of  the  Rockport 
Granite  Co.,  Rockport,  and  also  at  the  Pomeroy  quarry,  Gloucester. 

Garnet.  Garnet  occurs  plentifully  in  a  garnet  schist  outcrop  between 
Powder  House  hill  and  White's  hill  in  Essex,  and  elsewhere  in  the  County. 


Fig.   I  19.— APORHYOLITE,    SHOWING    WEATHERED    SURFACE. 
High  Rocl<,  Marblehead  Necl<. 


Fig.   I  2  0. -BANDED    APORHYOLITE,    SHOWING    THE    FLOW    OF   THE    MAGMA    PREVIOUS    TO    ITS 

CONSOLIDATION.     SIZE    OF    SPECIMEN,    14  x   20    INCHES. 

Bowden's  Point,  Marblehead  Neck. 


THE    MINERALS     OF    ESSEX    COUNTY  241 

Almandite  Garnet.  Abundant  in  the  biotite  muscovite  granite  at 
Andover. 

Grossularite  Garnet:  Cinnamon  Stone.  In  a  drift  boulder  at 
Nahant. 

Zircon.  Crystals  with  double  terminations  are  abundant  in  the 
elasolite  zircon  syenite  at  Salem  Neck,  Beverly,  etc. 

Vesuvianite.  Specimens  from  a  vein  in  the  serpentine  at  the  Devil's 
basin,  Newbury,  were  analyzed  by  Prof.  W.  O.  Crosby,  and  determined 
as  vesuvianite. 

Epidote.  Veins  with  fine  drusy  crystals  are  found  at  Egg  rock,  near 
Nahant;  in  the  diabase  at  East  point,  Nahant;  and  also  in  the  rhyolites 
at  Marblehead,  Clifton,  etc. 

Allanite.  Radiated  crystals  are  foimd  in  the  diorite  at  Beverly, 
and  long  slender  crystals  are  found  in  the  augite  syenite  at  Beverly  and 
West  Gloucester  and  in  the  granite  at  Swampscott.  The  specimen  deter- 
mined as  orthite  and  described  in  the  "American  Journal  of  Science 
and  Arts,"  Vol.  XXXIII,  page  198,  should  undoubtedly  be  referred  to 
Allanite. 

Orthite.  Found  in  radiated  crystals  in  the  hornblende  biotite  grani- 
tite  at  the  quarry  of  the  Rockport  Granite  Co.,  Rockport. 

ZoisiTE.  This  occurs  in  fine  blue  crystalline  masses  in  the  zoisite 
gneiss  and  the  hornblende  epidote  gneiss  at  Andover,  Georgetown,  and 
Newbury. 

loLiTE.     Found  in  corderite  gneiss  at  Marble  Ridge,  North  Andover. 

Phlogopite  Mica.     In  granitite  at  Rockport. 

BioTiTE  Mica.  In  augite  syenite  at  Salem  Neck  and  Beverly,  and 
also  in  granitite  at  Rockport. 

Lepedomelane.  Found  in  hexagonal  plates  of  a  bronze  color  in  the 
Pomeroy  quarry,  Gloucester. 

AsTROPHYLLiTE.  In  the  quarry  of  the  Rockport  Granite  Co.,  Rock- 
port. 

Muscovite  Mica.  Common  in  the  biotite  muscovite  granite  at 
Andover,  Methuen,  and  Rowley. 

Lepidolite:  Lithia  Mica.  In  mica-schist  at  Ballardvale,  Andover, 
Ward's  Hill,  Bradford,  and  Methuen. 

Sericite.  This  occurs  in  irregularly  banded  plates  in  the  jaspelite 
at  Saugus  Centre,  etc. 

Scapolite:  Wemerite.  In  1890,  microscopic  grains  of  scapolite  were 
discovered  in  thin  sections  of  the  hornblende  granite  collected  at  a  quarry 


242 


THE    MINERALS    OF    ESSEX    COUNTY 


on  Humphrey  street,  Swampscott,  which  is  beheved  to  be  the  only  record 

of  this  mineral  having  been  found  in  granite. 

Cryophyllite.     In  the  hornblende  biotite  granitite  at  Rockport/ 
Annite.     FotHid  in  the  hornblende  granite  at  Rockport.^ 

^  Chemical  analyses  of  three  sections  of  cryophyllite  from  Rockport,  made  by  R.  B. 
Riggs,  of  the  United  States  Geological  Survey,  gave  the  following  results. 

A.  Brilliant,  broadly  foliated,  blackish-green  variety. 

B.  Paler,  dull  green,  less  Ittstrous,  probably  somewhat  altered. 

C.  Granular,  resembling  chlorite,  minute  six-sided  prisms,  color  dark  green. 


SiO^ 

A1203 

FeO 

MnO 

CaO 

MgO 

LijO 

NajO 

KjO 

H,0 

P 


Less  oxygen — O     equivalent  to  F  2.86 


A 

B 

C 

51-96 

51-46 

52-17 

16 

89 

16.22 

16.39 

2 

63 

2.21 

4. 1 1 

6 

35 

7.66 

6.08 

24 

.06 

■32 

12 

traces 

traces 

°3 

•17 

traces 

4 

93 

4.83 

5-°3 

92 

-95 

.60 

10 

66 

10.65 

10.54 

1 

26 

1.06 

1-43 

6 

78 

7-44 

7.02 

102.77 

102.71 

103.69 

2 

.86 

3-II 

2-95 

99.60 


^  A  chemical  analysis  of  the  annite  from  Rockport,  made  by  R.  B.  Riggs  of  the  United 
States  Geological  Survey,  gave  the  following  result: 

SiOj      32.03 

TiO^ 3-42 

AI2O2 11.92 

Fe^Oj 8.00 

FeO      30.41 

MnO .21 

CaO 23 

MgO 06 

NiOCoO  

LijO traces 

Na^O 1.54 

KjO      8.46 

HjO  at  105°         1 

H^O  above  105°  J      '^•'^ 


100.47 


Fig.  121.  — APORHYOLITE    CONCRETION,    9    INCHES    IN    DIAMETER. 
Marblehead  Neck. 


Fig.   122.— APORHYOLITE    CONGLOMERATE,    12x14   INCHES    IN     SIZE. 
South  Gooseberry  Island,  Salem  Harbor. 


THE    MINERALS    OP    ESSEX    COUNTY  245 

El^olite.  This  occurs  in  large  irregular  crystalline  masses  in  the 
elseolite  zircon  syenite  at  Beverly,  Salem  Neck,  etc. 

Nephelite:  Nepheline.  Found  in  small  micro-crystals  in  the  augite 
nepheline  syenite  at  Salem  Neck,  Beverly,  and  Gloucester. 

Cancrinite.  This  occurs  in  minute  irregular  masses  in  the  elseolite 
zircon  syenite  at  Salem  Neck  where  it  is  lemon  yellow  in  color.  It  is  more 
abundant  at  Great  Haste  ledge  and  the  Ram  islands,  Salem  harbor,  where 
the  color  is  grayish  to  brown. 

SoDALiTE.  In  coarse  pegmatitic  masses  in  the  elaeolite  zircon  syenite 
at  Salem  Neck,  Great  Haste  ledge,  and  Beverly  shore. 

Hydronephelite.  In  radiated  crystals  in  the  elseolite  zircon  syenite 
at  Salem  Neck. 

Anorthite.  a  large  mass  of  this  feldspar  occurs  at  East  point, 
Nahant,  near  the  residence  of  Hon.  H.  C.  Lodge. 

Labradorite.  This  occurs  in  large  crystals,  some  of  which  are  three 
inches  long  by  one  and  one  half  inches  wide,  in  the  gabbro  at  Bay  View, 
Davis  Neck,  and  Lanesville  in  Gloucester;  also  in  porphyritic  dike  rocks 
in  various  localities. 

Albite.  Fine  glassy,  multiple-twinned  crystals  are  found  at  the 
Pomeroy  quarry,  Gloucester. 

Orthoclase.  Simple  and  twinned  crystals  are  found  in  pegmatitic 
masses  in  the  granite  at  Rockport.     Common  in  the  granite. 

Microcline:  Amazon  Stone.  Specimens  of  a  bright  verdigris-green 
color  are  found  at  Briscoe  hill,  Beverly,  and  at  Gloucester,  and  Rockport. 

Microcline  microperthite  :  Soda  Microcline  of  Brogger.  Found  in 
coarse  crystalline  masses  in  the  eteolite  zircon  syenite  at  Salem  Neck. 

Orthoclase  microperthite  :  Albite  and  Orthoclase  intergrowths.  In 
the  elffiolite  zircon  syenite  at  Coney  island,  Salem  harbor. 

Sanadin.  In  crystals  from  the  Bostonite  porphyry  (Rosenbusch) ,  a 
dike  rock  on  Coney  island,  Salem  harbor. 

Anorthoclase.  In  crystals  in  the  keratophyre  at  Marblehead  har- 
bor.» 

Prehnite.  Rare;  in  reniform  or  globular  masses  in  the  hornblende 
gabbro  at  Nahant. 

Natrolite.  This  occurs  as  a  secondary  pseudomorph  of  elaeolite  on 
Salem  Neck  and  in  amygdules  in  the  amygdaloidal  melaphyre  at  Rowley. 

Steatite:  Soapstone.  In  a  massive  bed  associated  with  the  serpen- 
tine at  Newburyport. 

»   See  Bull.  M.  C.  Z.,  Geol.  Sur.,  Vol.  II,  No.  9,  p.  167. 


246  THE    MINERALS    OF    ESSEX    COUNTY 

Talc.     The  fine  granular  variety  known  as  French  chalk  is  found  at 
Newburyport  near  the  silver  mines. 

Serpentine  :  Noble  Serpentine.      Of  a  rich  oil-green  color  at  Devil's 
den,  Newbury. 

Serpentine  :  Common  Massive  Serpentine.     At  Devil's  den,  Newbury. 

Serpentine  :  Foliated  Serpentine :  Marmolite.  At  Devil's  den,  New- 
bury. 

Serpentine  :  Picrolite.     At  Devil's  basin,  Newbury. 

Serpentine  :  Picrosmine.     At  Devil's  basin,  Newbury. 

Serpentine:  Baltimorite.     At  Devil's  basin,  Newbury. 

Serpentine  :  Chrysotile :  silky  fibrous.     At  Devil's  basin,  Newbury. 

Serpentine:  Massive  Serpentine,  dark  colored  variety.  At  Lynn- 
field  Centre. 

Kaolinite.  At  Kent's  island,  Newbury,  and  at  Little  Niagara  river, 
Bradford. 

Tourmaline.  Long  acicular  crystals,  some  of  which  in  finely  radiated 
groups  and  black  in  color,  are  found  at  South  Groveland. 

Andalusite.  In  veins  of  andalusite  slate  at  Nahant,  and  near  Flax 
pond,  Lynn. 

Andalusite:  Chiastolite.  Crystals  are  found  in  glacial  drift  at  the 
Castle,  Castle  river,  Ipswich. 

Fibrolite.     In  the  corderite  gneiss  at  Marble  Ridge,  North  Andover. 

Titanite:  Sphene.  Micro-crystals  are  found  in  augite  syenite  at 
Salem  Neck,  Beverly,  Magnolia,  etc. 

Bastite;  Schiller  Spar.  Resulting  from  the  alteration  of  pyroxine 
diallage  in  the  diabasic  norite,  Nahant. 

Finite.  Pseudomorph  of  orthoclase;  at  Eagle  island,  Little  river, 
and  Kent's  island,  in  Newbury,  etc. 

Jeffersite.  In  broad  crystalline  plates  resembling  biotite  mica ; 
northwest  side  of  Powder  House  hill,  Beverly,  and  in  the  old  lime-pits 
near  Stevens'  pond,  Boxford. 

Pennenite.     In  the  Pomeroy  quarry,  Gloucester. 

Delessite.  This  occurs  as  thin  folia  in  seams  of  diorite  at  Salem, 
and  in  diabase  dike  rock  at  Bradford,  etc. 

Uralite.  a  paramorph  of  hornblende  after  pyroxene.  This  min- 
eral is  abundant,  microscopically,  in  the  quartz  augite  diorite  of  New- 
buryport, Carr's  island,  etc. 

Fergusonite.  Found  in  the  granite  at  the  quarry  of  the  Rockport 
Granite  Co.,  Rockport. 


THE    MINERALS    OF    ESSEX    COUNTY  249 

Ruby  Spinel.  Rose  colored  specimens  in  massive  form  were  fotmd  in 
the  limestone  at  East  point,  Nahant,  in  1905. 

Apatite:  Phosphate  of  Lime.  Microscopic  crystals  occur  abundantly 
in  diorite  augite  syenite,  and  many  dike  rocks. 

Apatite:  var.  Guano.  Found  incrusting  the  rocks  at  Great  Haste 
ledge  and  Halfway  rock,  Salem  harbor. 

Calcite:  Calc  Spar.  Often  found  in  good  rhombic  crystals  in  the 
amphibolite  gneiss  at  Putnamville. 

Calcite:  Dogtooth  Spar.  Near  the  Tri-Mountain  House,  Bass  Point 
Nahant. 

Calcite  :  Massive  Granular  Limestone.  Found  in  large  masses  at  the 
Devil's  den  and  Devil's  basin,  Newbury,  and  at  the  old  lime-pits  in  Box- 
ford. 

Calcite  :  Massive  Blue  Limestone.  Interstratified  with  quartzite  sand- 
stone and  slate  in  the  carboniferous  rocks  at  Topsfield. 

Calcite:  Statuary  Marble.  Specimens,  pure  white  and  fine  grained, 
occur  at  the  Devil's  den,  Newbury. 

Calcite:  Silicious  Limestone.  This  belongs  to  the  Olenellus  Lower 
Cambrian  period  and  occurs  at  Archelaus  hill,  West  Newbury,  at  Rowley, 
and  Nahant. 

Dolomite:  Magnesian  Limestone.  Found  in  veins  in  the  serpentine 
at  the  Devil's  den,  Newbury. 

Ankerite.  Good  rhombohedral  crystals  are  fotmd  in  the  granite  at 
the  Pomeroy  quarry,  Gloucester. 

Magnesite  :  Brown  Spar.  Found  in  the  old  serpentine  ledge  at  Lynn- 
field  Centre,  and  at  Boxford  and  Newbury. 

Siderite:  Spathic  Iron.  Massive  crystalline  forms  are  found  asso- 
ciated with  the  iron  pyrites  and  galena  at  the  Chipman  mine,  'Newbury, 
and  (rare)  in  small  compound  scalenohedrons  and  rhombic  crystals  in- 
crusting  the  albite  feldspars  at  the  Pomeroy  quarry,  Gloucester. 

Siderite,  bronze  var.  In  the  Newbury  mining  region.  The  usual 
form  is  granular  in  structure. 

Malachite:  Green  Carbonate  of  Copper.  Found  associated  with 
gray  copper  at  the  Osgood  mine,  South  Georgetown. 

Azurite:  Blue  Carbonate  of  Copper.  At  the  Osgood  mine,  South 
Georgetown. 

Quartz.  A  quartz  crystal,  an  inch  broad,  a  pseudomorph  of  fluorite, 
deep  scarlet  in  color,  was  found  in  the  granite  at  the  quarry  of  the  Rock- 
port  Granite  Co.,  Rockport. 


250  THE    MINERALS    OF    ESSEX    COUNTY 

Coal:  Earthy  Brown  Coal.  At  the  east  side  of  Nahant,  near  the 
old  iron  mine. 

Bog-butter:  Oxygenated  Hydrocarbon.  Three  feet  oelow  the  sur- 
face, at  Clifton,  Marblehead. 

Yttrocerite.  On  massive  smoky  quartz  in  the  Rockport  Granite 
Company's  quarry,  Rockport. 


CHAPTER  X 

THE    QUATENARY   PLEISTOCENE    PERIOD  :    GLACIAL    ICE    EPOCH 

The  landscape  of  Essex  County,  and  in  fact  of  all  New  England,  owes 
its  generally  rounded  outline  and  level  sky-line  to  the  effect  of  an  ice- 
sheet,  or  continental  glacier,  which  covered  this  region  in  the  ice  epoch. 
(See  Fig.  124.)  The  thickness  of  this  ice-sheet  is  computed  to  have  been 
at  least  2,290  feet.  The  summit  of  Mount  Desert  island,  on  the  coast  of 
Maine,  is  glaciated  with  fine  strise,  or  scratches,  at  an  elevation  of  1,527 
feet  above  mean  sea-level.  Prof.  Louis  Agassiz  is  quoted  as  saying, 
that  no  glacier  could  cross  a  ridge  unless  its  thickness  was  at  least  one 
half  of  the  height  above  the  ridge,  and  by  this  rule  it  may  be  judged  that 
the  ice-sheet  on  the  coast  of  Maine  was  763  feet  in  thickness  over  the 
summit  of  Mount  Desert.  To  this  should  be  added  the  height  of  Mount 
Desert —  1,527  feet,  giving  a  total  thickness  of  the  ice-sheet  above  mean 
low  water  on  the  coast  of  Maine  of  at  least  2,290  feet.  As  there  is  no  ma- 
terial difference  between  mean  low  water  at  Mount  Desert,  and  at  Essex 
County,  it  is  fair  to  presume  that  the  ice-sheet  over  the  latter  region  was 
also  at  least  2,290  feet  in  thickness.  Inland  from  the  coast  one  hundred 
and  twenty-five  miles  is  Mount  Greylock,  the  highest  elevation  in  the  state 
and  3,555  feet  above  mean  low  water  (Appalachian  Club).  By  follow- 
ing the  rule  laid  down  by  Professor  Agassiz,  the  thickness  of  the  ice-sheet 
in  the  Mount  Greylock  region  must  have  been  5,301  feet,  indicating  a 
gradual  slope  of  sixteen  feet  to  the  mile  from  Mount  Greylock  to  the  coast 
of  Essex  County. 

At  the  close  of  the  Tertiary  period  and  during  the  ushering  in  of  the 
Quaternary  or  Pleistocene  period,  occurred  the  great  uplift  or  elevation 
of  the  land  surface  amounting  to  several  thousand  feet  in  North  America. 
Probably  this  uplift  was  from  one  hundred  and  eighty  to  two  hundred 
feet  in  Essex  County.  It  raised  the  bed  of  the  sea  to  high  land  from  one 
to  two  hundred  miles  out  from  our  present  coast  for  the  distance  reaching 
from  Jeffery's  shoal  to  beyond  Cape  Sable.  This  uplift  caused  the  rivers 
and  streams  to  cut  down  their  valley  beds,  thus  forming  the  deep  fiord- 
like channels  and  hollows  which  now  reach  out  into  the  sea.     Another 

253 


254  THE    QUATENARY    PLEISTOCENE    PERIOD 

result  of  this  uplift  of  the  land  surface  was  to  change  the  climate  from 
temperate  to  boreal.  This  arctic  climate  caused  a  glacial  ice-cap  to  form 
over  the  uplifted  land  surface.  It  expanded  from  a  center  of  accumula- 
tion in  the  Canadian  highlands,  and  moved  towards  the  southeast  from 
the  northwest,  which  is  the  direction  in  which  it  is  known  to  have  passed 
over  Essex  County  as  recorded  by  direction  of  the  grooved,  scratched, 
and  striated  surfaces  of  the  ledges  over  which  it  passed.  In  many 
places  it  planed  down  the  surfaces  and  rounded  the  outlines  of  hills  and 
ledges,  nearly  always  leaving  fine  scratches  and  striae  on  their  surfaces,  a 
lasting  record  of  glacial  action.  Some  times  even  the  tools  —  the  rocks 
with  which  these  scratches  and  grooves  were  made  —  are  found  in  the 
boulder-till.     (See  Fig.  126.) 

Glacial  erosion  is  shown  on  the  surface  of  bed-rock  by  grooves  and 
scratches,  or  striated  lines,  and  also  by  prominences  of  bed-rock  which 
have  been  rounded.  (See  Figs.  70,  127,  128.)  On  looking  northward 
from  the  top  of  Red  Shank  hill,  at  South  Georgetown,  the  land  surface 
appears  like  a  billowy  sea.  (See  Fig.  129.)  This  area  is  covered  by  a 
thin  coating  of  drift-sand  and  gravel,  and  the  true  nature  of  these 
mounds  is  not  apparent  until  the  sand  and  gravel  covering  is  removed, 
when  the  rounded  surfaces  of  the  bed-rock  appear.  The  name  Roches 
Moutonnees  or  "sheep  backs"  has  been  applied  to  this  formation.  A 
series  of  these  "sheep  backs,"  covered  with  drift  and  growths  of  forest 
trees,  occur  near  the  village  of  Topsfield,  and  have  received  the  local  name 
of  "sugar-loaf"  hills.  The  bed-rock  forming  these  elevations  in  Tops- 
field  is  arkose,  a  conglomerate  granite.     (See  Fig.  130.) 

In  nearly  all  parts  of  the  County,  the  surface  of  the  diorite  bed-rock, 
wherever  it  is  exposed,  is  distinctly  glaciated.  A  fine  example  of  a  glacial 
groove  in  a  hornblende  diorite  ledge  may  be  seen  beside  the  carriage  road 
in  Ledge  Hill  park,  Salem.  (See  Fig.  128.)  In  the  bottom  of  the  groove 
are  long,  deep  scratches  and  fine  striae,  and  beside  the  groove  and  on  its 
western  side,  the  whole  surface  of  the  ledge  is  glaciated  with  short  and 
long  grooves,  deep  scratches,  striae,  and  chatter-marks. 

Similar  glaciated  surfaces  of  bed-rock  may  be  seen  in  North  Salem. 
In  Danvers,  nearly  all  of  the  diorite  bed-rock  shows  glacial  scratches.  The 
direction  of  glacial  ice-movement  across  this  region  is  thereby  recorded 
as  having  been  from  the  northwest  to  the  southeast.  The  granite  and 
syenite  bed-rocks  also  show  glaciation,  but  the  scratches  and  striae  have 
usually  been  removed  by  disintegration,  leaving  only  the  rounded  sur- 
faces to  record  the  work  of  the  glacial  ice. 


Fig.  125.  — QUARRY    OF   THE    ROCKPORT   GRANITE    COMPAhJY    AT   ROCKPORT. 

Showing  the  general  structure  of  the  hornblende  granite  rock. 


1? 

■ 

■ 

|H| 

V  '^ 

■  'Sy 

jS[( 

jH| 

"wilP 

.^H^^^^H 

Hkm^^'*%i 

■ 

4 

w 

-■ 

I^^KK                39 

^^^K?/  '    '^     aH       ^ 

1^-y-  ■- 

^B 

IWBIvii'=Jl    ^ 

f^^ 

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] 

1 

Fig.  126.— GLACIATED- STONES    FOUND    IN    BOULDER-TILL   AT    NORTH    ANDOVER. 
J  stones  probably  were  some  of  the  tools  which  cut  the  glacial  grooves,  striae,  scratches,  and  chattermarks  found  c 
the  surface  of  outcropping  ledges. 


Fig.   127.  — GLACIATED    DIABASE    DIKE    ROCK    NEAR    FLYING    POINT,    MARBLEHEAD    NECK. 


Fig.   12  8.  — REMARKABLE    GLACIAL    GROOVE,   30   FEET    LONG,   3  FEET    WIDE,    AND    5   1-2    INCHES    DEEP,   ON 
THE    SURFACE    OF    A    HORNBLENDE    DIORITE    LEDGE    IN    LEDGE    HILL    PARK,    SALEM. 


ESKERS  259 

The  topography  of  Essex  County  therefore  owes  its  characteristic  fea- 
tures to  the  work  of  the  continental  glacier.  This  glacial  drift  assumes 
within  comparatively  limited  areas,  forms  so  numerous  and  so  varied  as  to 
render  the  region  an  exceptional  one  for  study.  The  bare,  rounded  surfaces 
of  the  granite  and  other  outcropping  bed-rocks  tell  the  story  of  a  grinding 
force.  The  long  sloping  hills,  the  drumlins  of  boulder-till,  the  "kettle- 
holes"  or  sites  where  icebergs  in  front  of  a  retreating  ice-sheet  had  been 
buried  in  over-wash  sands  and  gravels,  are  all  to  be  seen  in  various  parts 
of  the  County.  Ridges,  terraces,  and  cone-like  masses  of  sand  and  gravel 
rising  from  a  gently  sloping  incline  of  sand  and  clay,  and  leading  to  a 
pond  or  filled  pond,  now  a  peat  swamp,  alike  mark  the  contact  of  an  ice- 
block  that  was  stranded  at  the  present  location  of  the  pond  or  swamp. 
Moraines  or  circular  ridges  of  gravel,  and  boulder  trains  or  lateral  mo- 
raines sometimes  occupying  drainage  creases  in  front  of  the  retreating  ice- 
sheet,  are  among  the  forms  assumed  by  the  glacial  drift.  Another  form 
is  the  long  serpentine  ridge  or  esker  which  records  the  presence  of  a  drain- 
age stream  flowing  under  the  ice-cap  and  grading  its  channel  with  sand 
and  coarse  gravel.  Upon  emerging  from  under  the  ice  these  streams 
deposited  their  loads  of  sand,  gravel,  and  clay  in  the  order  of  their  coarse- 
ness, now  to  be  seen  in  the  form  of  bouldery  gravel-banks,  sand-plains, 
and  clay-beds. 

The  ideal  section  of  an  ice-contact,  with  alluvium  falling  against  the 
front  of  the  ice  edge  of  a  glacier,  will  very  well  represent  the  forma- 
tion of  the  kame  topography  on  the  south  side  of  Forest  river,  west  from 
the  electric  car  sheds,  in  Marblehead.  (See  Figs,  131,  132.)  These  ice- 
berg holes  are  locally  known  as  "the  dungeons."  They  were  formed  by 
detached  bergs  of  ice  which  became  buried  in  the  outwash  gravel.  When 
the  ice  melted,  the  covering  of  gravel  fell  in,  leaving  the  place  which  had 
been  occupied  by  the  ice-block  in  the  form  of  a  steep-sided  hole.  The 
ideal  section  demonstrates  that  an  alluvial  plain,  which  is  built  up  in  front 
of  a  glacier,  will  overtop  the  ice  and  include  not  only  morainic  debris  but 
also  blocks  of  the  ice,  and  when  the  glacier  melts,  the  overlapping  deposit 
cannot  assume  the  simple  earth  slope  of  the  angle  of  repose,  but  receives 
a  hummocky  morainic  appearance  as  illustrated  in  the  surface  from  the 
dotted  line  at  E  in  Fig.  132.     This  is  also  to  be  noted  in  Fig.  131. 

Eskers.  —  The  term  esker  is  here  employed  to  denote  distinct  ridges 
composed  chiefly  of  coarse  gravel,  angular,  subangular,  and  rounded 
boulders,  and  sand,  believed  to  have  been  deposited  in  the  beds  of  sub- 
glacial  streams,  being  phenomena   of  the  radial  drainage  of   the    conti- 


260  ESKERS 

nental  ice-sheet.  (See  Figs.  133,  134.)  Continuous  ridges  of  gravel,  de- 
noting subglacial  stream  channels,  are  of  rare  occurrence  in  eastern  Mas- 
sachusetts. There  are  numerous  curved  ridges  and  terraces  of  some  extent 
that,  without  doubt,  were  formed  by  gravels  deposited  from  the  sur- 
face of  a  waning  ice-sheet.  The  glacial  gravels  from  Bishop's  swamp, 
an  ice-block  hole  at  Danvers,  supply  an  example  on  a  small  scale.  (See 
Fig.  136.)  Many  similar  examples  both  large  and  small,  may  be  found 
in  all  parts  of  Essex  County.  Typical  eskers,  continuous  for  a  mile  or 
more,  as  previously  stated,  are  of  rare  occurrence. 

A  nearly  continuous  esker,  broken  by  post-glacial  erosion  and  stream- 
cutting,  may  be  traced  from  Groveland,  across  South  Groveland  to  the 
Parker  river  in  Georgetown,  and  then  across  Parker  river  to  Four  Mile 
pond,  in  Boxford.  At  the  northern  end  of  Four  Mile  pond  this  esker 
expands  into  a  rolling  sand-plain.  On  the  western  side  of  the  pond  it 
again  forms  into  a  steep-sided  ridge  which  extends  over  one  mile  to  the 
southeast,  where  it  is  obliterated  by  the  Pye  brook  sand-plain  in  Box- 
ford.  This  esker  is  next  seen  as  a  continuous  ridge  at  a  point  about  two 
miles  distant  and  north  of  Hood's  pond  in  Topsfield.  It  may  be  easily 
followed  in  the  valley  occupied  by  the  road-bed  of  the  Boston  and  Maine 
railroad  to  a  point  near  Bare  hill  in  Topsfield,  where  Mile  brook  and  a 
series  of  meadows  have  cut  through  and  destroyed  the  formation.  This 
esker  is  next  seen  in  a  hilly  pasture  on  the  land  of  John  Perkins,  south 
of  Mile  brook.  Here  it  becomes  very  distinct  and  forms  two  parallel 
ridges.  It  then  crosses  the  Ipswich  road  and  disappears  at  the  bank  of 
the  Ipswich  river.  On  the  other  side  of  the  river  this  ridge  may  be  traced 
around  the  northerly  side  of  Willowdale  hill  to  a  point  southerly  from 
the  site  of  the  Willowdale  mill,  where  it  is  flanked  on  the  east  by  a  remark- 
able series  of  reticulated  kames  exhibiting  both  knob  and  basin  topog- 
raphy, many  of  the  iceberg  holes  now  being  occupied  by  small  ponds. 
(See  Figs.  135,  138).  At  the  Gwinn  farm  in  Hamilton  this  esker  again 
appears  in  a  pasture,  where  the  top  of  the  ridge  might  be  observed  for  a 
■distance  of  over  a  mile  if  it  were  not  for  the  growth  of  small  trees  and 
bushes  which  cover  it.  South  of  the  Gwinn  farm  (see  Fig.  137)  it  crosses 
the  road  and  is  then  overgrown  with  hardwood  trees  for  a  distance  of 
nearly  five  htindred  yards  to  a  narrow  swamp.  Beyond  this  swamp  the 
ridge  again  appears  distinctly  with  very  steep  sides.  At  one  point  it  is 
■eighty  feet  from  the  top  of  the  ridge  to  the  level  of  the  low  land  in  the 
swamp  from  which  the  esker  rises.  This  section  is  continuous  for  over 
lialf  a  mile  to  the  tracks  of  the  Boston  and  Maine  railroad,  where  recent 


Fig.   129.  —  "  SHEEP    backs; 


OR   ROCHES  MOUTONNEES,    AT   SOUTH    GEORGETOWN, 
ons  of  bedrock  covered  by  drift  gravels. 


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Fig.   130.  — "  SUGAR-LOAF"   HILL  OR  ROCHE  MOUTONNEE  AT  TOPSFIELD. 
Arkose  granite  conglomerate  covered  by  a  thin  coating  of  glacial  drift. 


o  •■  '^  ". .     o 


Fig.     131.— IDEAL   SECTION    OF    AN    ICE    BLOCK    HOLE. 
The  profile  indicated  by  £,  marks  the  face  of  the  alluvial  deposit  after  the  ice 


j'j^S/E^U^^^S^ 


Fig.    132.  — IDEAL     SECTION    OF   AN    ALLUVIAL    PLAIN    BORDERING    THE    FRONT    OF    A  GLACIER. 


ESKERS  265 

excavations  for  gravel  have  destroyed  all  traces  of  it  for  two  hundred  yards. 
Beyond  the  railroad,  the  esker  continues  on  the  northerly  side  of  a  drumlin 
known  as  Lummus'  hill  and  extends  to  the  Hamilton  and  Ipswich  road, 
where  the  ridge  is  cut  away  and  replaced  by  a  sand-plain.  This  plain  is 
occupied  in  part  by  the  polo  grounds.  It  extends  to  Miles  river  and 
covers  the  whole  area  of  Wenham  and  Hamilton  as  far  as  the  village  of 
Wenham  on  the  west.  Across  Miles  river,  the  esker  becomes  a  series  of 
low,  rolling  ridges  and  kames,  which  extend  in  a  southwesterly  course 
and  follow  the  bank  of  Miles  river  for  a  distance  of  a  mile  to  the  swamp 
where  the  outlet  from  Beaver  pond  and  Norwood's  pond  joins  Miles 
river.  On  the  westerly  side  of  this  swamp,  and  south  of  the  rocky  hills, 
there  is  a  remarkable  ridge  or  series  of  ridges  which  is  without  doubt  com- 
posed of  overwash  gravels  from  the  ice  contact  in  Wenham  lake,  for  the  ■ 
ridge  gravels  may  be  traced  continuously  to  the  lake,  and  are  probably 
of  later  origin  than  the  esker  which  is  the  inner  or  northerly  ridge  and 
follows  the  base  of  the  hills  to  the  Longham  basin.  This  inner  ridge  is 
very  steep  and  high-sided,  and  in  places  becomes  divided  into  two  or  more 
ridges  with  deep  iceberg  holes  having  small  ponds  at  the  bottom.  (See 
Fig.  140.)  The  esker  then  winds  around  Norwood's  pond  and  forms  a  rolling 
ridge  on  its  eastern  side  (see  Fig.  139),  the  main  ridge  of  the  esker  being 
on  the  western  side  where  it  is  of  a  low,  rounded  form  showing  much  ero- 
sion on  its  surface,  which  is  deeply  furrowed  and  in  places  cut  down  nearly 
to  its  base.  Three  hundred  yards  to  the  southeast,  the  esker  expands 
into  a  sandy  gravel-plain,  which  is  cut  through  by  a  brook,  an  inlet  to 
Beaver  pond,  Beverly.  From  this  pond  the  esker  is  continuous,  with 
several  iceberg  holes  and  short  reticulated  kames,  to  Essex  street,  Beverly, 
where  it  divides  and  passes  on  both  sides  of  Turtle  hill,  a  large  granite 
outcrop,  at  the  south  of  which  it  develops  into  a  rolling  sand-plain  ex- 
tending to  Beverly  cove  and  Mingo  beach. 

This  is  the  only  continuous  esker  ridge  in  Essex  County.  There  are 
many  short  ridges,  more  probably  kames  and  ancient  barrier  beaches  or 
tombolas,  which,  with  a  stretch  of  the  imagination  may  be  connected  as 
parts  of  one  and  the  same  ridge  or  esker. 

Beaver  pond  in  Beverly  is  without  doubt  an  ice-block  hole,  as  on  the 
southeastern  side  of  the  pond  there  is  found  a  steep  incline  of  morainic 
drift  and  kame  gravels.  Norwood's  pond  was  formed  artificially  by  the 
construction  of  a  dam  between  the  Wenham-Beverly  esker  and  a  kame 
terrace  at  the  east. 

In  the  town  of  Danvers,  southwest  of  Nichols'  hill,  a  drumlin,  there  is  an 


266  ESKERS 

esker  which  may  be  readily  traced  in  a  serpentine  course,  from  Nichols' 
hill  to  Beaver  brook  and  then  southeasterly  to  Putnam's  mill  pond,  where 
it  skirts  Walnut  Grove  cemetery  on  the  south  and  crosses  Endicott  street 
to  the  John  Bates  farm,  where  it  is  cut  through  by  Water's  river.  Across 
the  river,  at  the  foot  of  Gardner's  hill,  it  winds  along  the  bank  of  Porter's 
river  into  North  Salem,  and,  crossing  the  North  river,  follows  in  a  some- 
what serpentine  course,  Essex  street  to  Boston  street;  then  sweeping  to 
the  south  between  Canal  street  and  Lafayette  street,  it  forms  a  series  of 
kames  on  the  Derby  and  the  Pickman  farms  lying  southwest  of  the  State 
Normal  School  in  South  Salem.  Across  Forest  river  it  becomes  a  series 
of  reticulated  kames  and  ridges  on  both  sides  of  Legg's  hill  (see  Figs.  141, 
143,  144)  and,  expanding  to  a  plain  at  the  east  of  Beach  Bluff  in  Marble- 
head,  it  sinks  into  the  sea  at  Phillip's  beach  in  Swampscott. 

A  ridge  which  is  possibly  a  remnant  of  an  esker  may  be  seen  about 
one  mile  east  of  Kimball's  pond,  in  Amesbury.  This  ridge,  which  is  quite 
serpentine  in  outline,  crosses  the  source  of  Bailey's  brook  and  continues 
parallel  with  it  and  on  its  easterly  side  to  the  Amesbury  and  Haverhill 
road.  At  the  north  side  of  the  road  there  are  good  examples  of  iceberg 
holes  and  short  reticulated  kames  with  the  usual  knob  and  basin  topog- 
raphy to  be  seen  in  a  region  where  icebergs  have  been  buried  in  glacial 
gravel.  Across  the  road  on  the  Davis  farm,  the  remnant  of  the  esker 
may  be  very  plainly  seen  in  the  form  of  a  circular  steep-sided  ridge,  which 
extends  to  the  northern  bank  of  the  Merrimac  river.  On  the  other  side 
of  the  Merrimac,  east  of  "The  Laurels"  and  near  the  old  ferry  road  from 
Newburyport  to  Salisbury  Point,  kames  and  iceberg  holes  become  very 
prominent  features  in  the  landscape.  From  the  ferry  road  to  High  street 
in  Newburyport,  the  whole  surface  of  the  area,  which  is  about  a  mile 
square,  is  a  rolling  sand-plain,  but  the  eastern  part  of  "  Grasshopper  plain," 
at  the  upper  end  of  High  street,  is  a  broad-topped  esker  which  extends 
the  whole  length  of  High  street  to  Old  Town,  in  Newbury,  and  out  into 
the  tidal-marsh  north  of  Parker  river.  There  are  several  sections  cut 
through  this  esker  on  High  street  near  Belleville,  which  show  that  it  rests 
upon  boulder-till  and  earlier  gravels. 

Another  esker  enters  Essex  County  from  Newton,  New  Hampshire, 
between  Brandybrow  hill  and  the  "Highlands"  in  Merrimac.  This 
esker  passes  over  the  stunmit  of  Red  Oak  hill  at  an  elevation  of  three 
hundred  and  twenty  feet  above  mean  sea-level  and  winds  in  a  north- 
easterly direction.  It  is  next  seen  on  the  west  bank  of  Cobbler's  brook 
and  extends  to  the  Merrimac.     Across  the  river  in  West  Newbury,  the 


Fig.   133.— THE    LONG    ESKER    NEAR    DODGE    STREET,    NORTH    BEVERLY. 


Fig.    134.  — THE    LONG     ESKER    NEAR   DODGE    STREET,    NORTH    BEVERLY. 
View  looking  northwesterly  across  Dodge  street. 


Fig.   135.— SERPENTINE    ESKER    AT    WILLOWDALE    IN    HAMILTON. 


Fig.   136.— BISHOP'S    SWAMP,    DANVERS,    AN    ICE-BLOCK    HOLE. 
View  from  the  base  of  Nichols'  hill  showing  the  gravels  deposited  from  the  surface  of  glacial 


EVIDENCES    OF    SEA    BEACHES    AT    INLAND    POINTS  271 

continuation  of  this  esker  may  be  traced  around  Long  hill  to  Indian  river, 
where  there  is  a  break  of  nearly  four  miles.  The  entire  surface  of  this 
region  is  covered  with  hard,  compact  boulder-till,  with  a  few,  compara- 
tively small  rounded  masses  of  gravel  resting  upon  it.  Short  ridges, 
which  may  represent  remnants  of  the  esker,  may  be  noted;  one,  south 
of  Archelaus  hill;  a  second,  southeast  of  Ilsley's  hill;  and  a  third  on  Moody 
street,  which  extends  to  Byfield  village.  At  the  southeast,  a  discontin- 
uous ridge  follows  the  west  bank  of  the  Parker  river  out  into  the  tide- 
water marsh  lying  east  of  the  Fatherland  farm  in  Byfield.  The  ridge  is 
next  seen  at  the  west  bank  of  the  Mill  creek  near  Glen  mills,  where  it  is 
nearly  continuous  for  about  a  mile,  but  is  divided  into  two  distinct  ridges 
at  Ox  Pasture  brook.  At  the  south  and  southeast  it  is  cut  off,  and  a  beach 
sand-plain  covers  the  region  on  which  the  village  of  Rowley  is  built.  Sand- 
ridges  and  plains  extend  southeasterly  between  the  drumlins,  Mussey 
hill  (see  Fig.  146)  and  Prospect  hill,  in  Rowley,  to  Bull  brook  and  the 
village  of  Ipswich.  South  of  the  brook  there  are  a  few  short  ridges  of 
water-washed  gravels  underlaid  by  clay-beds.  No  bouldery  cross-bedded 
esker  gravels  are  found  southeast  of  Rowley,  so  it  may  be  presumed  that 
the  course  of  the  esker  was  easterly  and  into  Ipswich  bay. 

In  the  northwestern  part  of  the  County,  an  esker  enters  Methuen  from 
Salem,  New  Hampshire,  a  mile  east  of  the  Spicket  river.  Pursuing  a 
winding  course  it  crosses  the  river  and  follows  its  west  bank  down  the 
valley  to  Stevens'  mill  pond,  and  beyond  it  in  a  southwesterly  direction 
to  the  Merrimac  river.  In  South  Lawrence,  the  sand-ridge  divides  into 
several  distinct  short  ridges  reaching  into  West  Andover,  one  being  the 
well-known  "Indian  ridge."  South  of  "Indian  ridge"  the  esker  is  lost 
in  post-glacial  sand-plains  and  short  curved  terraces.  Near  Pomp's  pond 
it  becomes  clearly  defined,  and  may  be  easily  followed  half  a  mile  beyond 
Ballardvale,  where  it  disappears  in  a  sand-plain,  probably  an  inland  sea 
beach  which  covers  an  area  of  about  two  miles  square  and  extends  to 
Reading  in  Middlesex  County.  The  composition  of  these  sand-terraces 
is  of  the"  same  grayish-white  fine  sand  that  is  found  on  beaches  along  the 
coast,  and  does  not  in  the  least  resemble  the  reddish  sand  of  the  esker 
and  ice-contact  series,  the  sands  and  gravels  of  the  esker  at  Hamilton 
and  Beverly  in  particular.  The  southwesterly  part  of  Andover  is  cov- 
ered with  a  nearly  horizontally-bedded  sand  which  extends  downward 
almost  to  the  surface  of  the  bed-rock  on  top  of  which  is  boulder-till,  but 
seldom  more  than  a  few  feet  in  thickness. 


2T2  EVIDENCES    OF    SEA    BEACHES    AT    INLAND    POINTS 

Evidences  of  Sea  Beaches  at  Inland  Points.  —  During  the  Interglacial 
or  Champlain  period,  there  was  a  corresponding  subsidence  of  the  land 
surface  which  again  changed  the  climate  from  arctic  to  boreal.  During 
this  period  the  ice-cap  melted  and  wasted  away,  and  the  land  sank  below 
the  level  of  the  sea  to  a  depth  of  two  hundred  feet  or  more.  This  depth 
of  subsidence  is  proved  by  finding  in  our  marine  clay-beds,  specimens 
of  fossil  moUusks  which  live  at  that  depth  in  the  high  Arctic  seas.^  There- 
fore it  may  be  presumed  that  these  moUusks,  which  are  of  the  same  species 
and  size  as  those  found  in  Norway,  lived  at  the  same  depth  on  our  coast 
during  this  Interglacial  period. 

The  subsidence  during  the  Champlain  period  caused  the  whole  land 
surface,  including  the  highest  peaks  of  outcropping  ledges  in  the  County, 
to  sink  below  the  surface  of  the  sea,  and  the  ledges  and  hills  which  had 
been  cut  down,  rotmded,  and  smoothed  by  glaciation,  were  then  stripped 
of  their  debris  by  the  action  of  the  waters.  The  results  of  wave  and  sea 
action  are  to  be  seen  in  many  parts  of  the  Cotmty.  Sand  and  gravel 
beds,  comparable  only  with  sea  beaches,  are  often  found  in  localities  remote 
from  ice  contact.  These  are  composed  of  coarse  gravels  in  which  all 
the  pebbles  and  stones  are  rounded  and  smoothed  as  in  sea-washed  shin- 
gles. Some  ridges  are  also  composed  of  wave-washed  sands,  round  beach 
pebbles,  and  stones  of  exactly  the  same  material  as  those  found  to-day 
in  making  an  excavation  through  the  barrier  of  a  sea  beach.  Examples 
of  such  debris  may  be  found  in  all  parts  of  the  County.  At  Reading,  in 
Middlesex  County,  there  is  such  a  deposit  which  extends  toward  the  north 
and  covers  a  large  part  of  Wilmington  and  Andover.  Here  the  fine  silts 
and  sands  are  water-laid,  and  the  coarse  gravels  contain  stones  and  peb- 
bles worn  round  and  smooth  like  similar  deposits  on  the  sea  beaches. 
Numerous  road-cuttings  and  gravel-banks  reveal  the  fact  that  the  bedding 
of  these  deposits  is  horizontal  with  hardly  a  trace  of  cross-bedding,  save 
in  some  restricted  areas.  The  presence  of  a  shearing  or  cross-bedded 
area  in  the  otherwise  horizontally-bedded  sands  is  explained  by  the  flow 
of  cross  and  counter  currents  below  the  surface.  Several  of  the  ridges 
at  Andover  are  dotted  with  numerous  large  boulders,  and  where  cuttings 
have  been  made,  these  boulders  are  found  to  be  equally  abundant  below 
the  surface  and  intermingled  with  the  fine  water-laid  sand  and  silt  of 
which  the  ridges  are  composed.  Numerous  cross-sections  of  these  ridges, 
with  hanging  boulders,  may  be  seen  along  the  road-bed  of  the  Boston 

*  Professor  Brogger — "Late  and  Post-Glacial  Changes  of  Level  in  the  Region  of 
Kristiania,"  pp.  156-159. 


Fig.    137. —SERPENTINE    ESKER   ON   THE    GWINN    FARM    NEAR   WILLOWDALE    IN    HAMILTON. 


Fig.    138. —  SERPENTINE   ESKER  AT  WILLOWDALE    IN    HAMILTON. 
Illustrating  reticulated  kames,  and  knob  and  basin  topography.     The  small  pond  is  at  the  bottom  of  an  ice-berg  kettle  hole 


Fig.    139.  — NORWOOD'S    POND,    NORTH    BEVERLY,    HAVING    ESKER    TERRACES    ON    BOTH    SIDES. 
View  from   the   main   terrace. 


Fig.    140,  — DOUBLE    TERRACE    ESKER    ON    THE    NORTH    SIDE    OF    LONGHAM    BROOK,    WENHAM. 
Showing  a  kettle  he  e. 


SUBGLACIAL    DRUMLINS  277 

and  Maine  railroad  in  Wilmington  and  Andover.  There  is  but  one  ex- 
planation for  the  presence  of  boulders  in  these  fine  silts  and  sands.  They 
must  have  been  dropped  from  the  bottom  of  floating  ice,  as  this  inland 
sea  was  not  of  sufficient  depth  to  float  an  iceberg  large  enough  to  carry 
a  load  of  these  boulders. 

Sea-worn  gravels  may  be  seen  in  the  niunerous  road-cuttings  along  the 
line  of  the  electric  road  between  Georgetown  and  South  Groveland.  Here 
the  same  rounded  beach-worn  gravels  appear  horizontally-bedded  with  the 
sands,  but  exhibiting  no  trace  of  cross-bedding,  even  in  sections  of  ridges. 
Grasshopper  plain,  west  of  Belleville,  at  Newburyport,  is  another  ex- 
.  ample  of  an  inland  marine  beach.  The  fine  sand  and  slits  on  the  surface 
vary  from  a  few  feet  to  ten  feet  in  depth,  and  below  these  sands,  sea-worn 
pebbles  of  slaty  rocks  predominate,  rounded  on  their  edges  like  the  slaty 
pebbles  found  at  Boar's  head  and  Hampton  beach  in  New  Hampshire. 
The  conclusion  is  inevitable  that  these  deposits  of  sand  and  sea-worn 
pebbles  indicate  old  sea  beaches  that  were  formed  during  the  Interglacial 
and  Champlain  epochs  of  the  Pleistocene  period. 

Subglacial  Drumlins.  —  Boulder-till,  the  gi^nd  moraine  of  many  authors, 
is  a  compact,  unstratified  mass  of  glacial  debris,  composed  of  clay, 
sand,  gravel,  pebbles,  and  boulders,  mixed  together  in  a  heterogeneous 
mass  without  stratification  of  its  members.  (See  Figs.  145,  147,  148,  150.) 
It  was  formed  under  and  incorporated  in  the  basal  portion  of  the  ice-sheet. 
Some  of  the  boulders  are  glaciated  —  smoothed  or  polished  and  scratched 
with  fine  lines  or  stvise  on  some  parts  of  their  surfaces.  Small  boulders 
and  pebbles  are  invariably  glaciated.  The  bed-rock,  in  all  parts  of  the 
County  where  it  can  be  examined,  is  covered  by  a  layer  of  this  boulder- 
till,  varying  in  thickness  from  a  few  inches  to  over  one  hundred  feet. 

Drumlins  are  composed  of  two  kinds  of  materials.  The  upper  portion, 
which  is  from  six  to  forty  feet  in  thickness,  is  usually  found  to  be  com- 
paratively loose  reddish-yellow  till,  with  numerous  boulders  which  fre- 
quently are  of  large  size.  .This  kind  of  till  is  thought  to  have  been  formed 
in  and  on  top  of  the  waning  ice-sheet  at  the  close  of  the  Glacial  period, 
and  at  its  final  disappearance,  to  have  been  deposited  on  top  of  the  true 
ground  moraine  or  boulder-till,  and  thus  the  upper  portion  which  is  ex- 
posed to  view  is  englacial  and  not  true  subglacial  till.  The  lower  portion 
of  the  drumlins  is  composed  of  blue  clay,  sand,  gravel,  and  boulders, 
without  any  system  of  arrangement  of  the  different  component  parts. 
Occasionally  the  small  boulders  and  pebbles  are  somewhat  triangular  in 
shape,  and  are  scratched,  smoothed,  and  sometimes  polished  on  all  their  sur- 


278  WASH-PLAINS 

faces  as  if  they  had  often  served  as  abrading  tools  while  frozen  into  the 
lower  surface  of  the  ice-sheet ;  from  that  position  to  be  dislodged  and,  after 
rolling  over  and  over,  again  to  become  frozen  into  the  ice,  thereby  exposing 
a  fresh  surface  to  continue  the  process  of  smoothing  and  scouring  the  bed- 
rock over  which  the  glacial  ice  passed,  until  at  last  they  were  deposited 
in  the  boulder-till  where  we  find  them  to-day.  A  drumlin  near  the  Shaw- 
shene  river  at  North  Andover  contains  many  such  triangular,  scratched, 
and  smoothed  boulders  and  pebbles.  (See  Fig.  126.)  In  other  drumlins, 
these  forms  of  scratched  stones  are  rare,  and  smoothed  and  scratched  blocks 
with  rounded  edges  are  the  rule.  Such  blocks  are  rarely  composed  of 
hard  rocks.  Small  pebbles  of  quartz,  usually  subangular  in  form  and 
somewhat  smoothed  upon  their  surfaces,  are  often  found  in  the  boulder- 
till.  Without  doubt  these  were  the  tools  that  produced  the  deep  grooves, 
scratches,  and  chatter-marks  so  often  seen  upon  the  surfaces  of  the  granite 
and  diorite  bed-rocks. 

In  Essex  County,  there  are  one  hundred  and  seventy-three  drumlins,  and 
one  hundred  and  seven  thousand,  five  hundred  and  twenty  acres  of  boulder- 
till  soils  which  are  very  fertile  for  the  agriculturalist.  Hog  island,  in  the 
town  of  Essex,  is  a  typical  specimen  of  a  drumlin.    (See  Figs.  145,  149.) 

Wash-Plains.  —  The  mode  of  deposition  of  the  wash-plains  in  this 
region  affords  a  clue  to  the  relative  areas  of  stagnant-ice  and  live-ice  dur- 
ing the  retreat  of  the  glacier  from  this  area.  The  conditions  demanding 
stagnation  are  found  in  the  numerous  ice-block  depressions  and  wash- 
plains  with  heads  which  show  no  forward  movement  of  the  ice-sheet, 
either  by  the  failure  of  shoving  in  the  gravels,  or  by  the  lack  of  morainal 
deposits  in  the  terrace  at  the  heads  of  the  wash-plains. 

The  facts  demanding  live-ice,  at  intervals  during  the  retreat,  are  the 
lines  of  boulder-belts,  or  positions,  marking  halts  of  the  ice-front,  during 
which  backward  melting  equalled  forward  movement. 

The  boulder-belts  at  Cape  Ann  and  at  Newbury,  in  the  Byfield  area, 
were  probably  deposited  when  the  ice-cap  at  the  north  was  still  live-ice, 
in  which  there  was  a  forward  movement  and  also  general  retreat.  Every 
forward  movement  of  the  ice-sheet  would  reduce  and  obliterate  all  former 
wash-plains  laid  down  during  the  retreat  of  the  ice  over  the  area,  and 
except  in  areas  far  in  front  of  the  ice  advance,  wash-plains  and  delta-fans 
would  be  built  up  on  former  wash-plains,  thus  making  the  composite  struc- 
tures we  find  to-day  reaching  in  a  north-northwesterly  course  across  the 
County  and  well  into  New  Hampshire. 

In  South  Salem,   on  Broadway,  masses  of  boulder-till  and  clay  are 


Fig.    141.  — KAMES    AND    KETTLE    HOLES    NEAR    FOREST    RIVER. 


Fig.    142.  — STEEP-SIDED    ESKER    WEST    OF    NORWOOD'S    POND. 
North    Beverly. 


Fig.    143.  — KNOB    AND    BASIN    TOPOGRAPHY,   SHOWING    KETTLE    HOLES    SOUTHWEST    OF  THE 
"DUNGEONS"    IN    MARBLEHEAD. 


Fig,    144,— GLACIAL  TILL  AND    GRAVEL  CONE   ON    THE    SOUTH    SIDE   OF    FOREST   RIVER,  SALEM. 


KAMES    AND    ICE-BLOCK    HOLES  283 

found  between  gravels  of  an  earlier  and  a  later  wash-plain,  showing  at 
this  point  the  retreat  of  the  ice  when  the  lower  gravels  were  deposited, 
and  an  advance  when  the  boulder-till  was  formed  upon  the  earlier  gravels, 
and  then  a  later  retreat  in  which  the  surface  deposit  or  thin  sheet  of  gravel 
and  sand  was  laid  down. 

Without  doubt  there  are  many  such  local  deposits  near  the  sea-coast 
showing  two  or  more  advances  and  retreats  of  the  glacial  ice-sheet  or,  at 
least,  deposits  caused  by  local  glaciers  which  have  advanced,  and  depo- 
sited boulder-till,  and  then  retreated  during  a  series  of  warm  seasons 
when  over  and  outwash  gravels  were  equally  laid  down;  but  it  is  very 
doubtful  if  such  retreats  and  advances  occurred  away  from  the  imme- 
diate seashore.  In  Lawrence,  Haverhill,  and  Andover,  there  has  been 
extensive  cutting"  away  and  levelling  of  hills  for  streets,  but  the  cross- 
sections  have  not  shown  examples  proving  more  than  one  advance. 

It  would  therefore  appear  that  when  the  drumlins  and  boulder-till 
were  deposited,  and  the  ice-sheet  had  retreated  from  the  region,  the  kame- 
gravel  wash-plains  and  other  phenomena  of  the  drift  were  laid  down.  This 
is  clearly  due  to  the  Champlaih  subsidence  and  the  later  elevation  of  the 
land  surface. 

Karnes  and  Ice-block  Holes.  —  Wash-plains  appear  in  the  form  of 
gently  sloping  areas,  composed  of  stratified  gravel  and  sand,  deposited 
along  the  ice  front.  Many  wash-plains  are  interrupted  by  depressions, 
or  amphitheater-like  hollows,  illustrating  the  formation  of  "kettle  holes" 
and  the  slope  of  kame-terrace  gravels  in  front  of  the  retreating  ice-sheet. 
(See  Figs.  154,  155.)  The  term  kame  is  used  in  the  generally  accepted 
sense,  as  designating  deposits,  chiefly  of  sand  and  gravel,  having  a  knob 
and  basin  topography,  and  formed  at  the  margin  or  periphery  of  the 
ice-sheet,  or  in  front  or  over  ice-blocks.  Examples  of  ice-contacts  left 
at  intervals  to  show  the  retreat  of  the  ice  in  its  final  melting  are  seen 
in  various  parts  of  the  County.  One  excellent  example,  in  which  there 
are  a  series  of  ice-block  holes  on  a  small  scale,  is  the  overwash  gravel- 
and  sand-plain  in  Marblehead,  near  the  Salem  boundary  line.  This  con- 
tact was  formed  when  the  retreating  ice  front  was  in  Forest  river,  reach- 
ing out  into  Salem  harbor.  The  ridge  marking  the  contact  is  irregular 
in  outline,  and  extends  on  the  south  side  of  the  bed  of  the  river  around 
Legg's  hill,  a  massive  outcrop  of  hornblende  diorite  rock  that  rises  one 
hundred  and  sixty-five  feet  above  mean  low  water.  ^    (See  Figs.  156,157,158.) 

An  ice-block  hole  near  Legg's  hill  is  now  represented  by  a  small  pond  known  as 
Legg's  Hill  pond.     This  pond,  which  is  fast  disappearing  under  the  swampy  peat  that  is 


284  KAMES    AND    ICE-BLOCK    HOLES 

These  numerous  crater-like  hollows,  locally  called  "dungeons,"  and 
amphitheater-like  depressions,  mark  small  ice-block  holes  when  berg-ice, 
detached  from  the  ice  front,  became  covered  by  the  overwash  sand  and 
gravel,  and  upon  the  melting  of  the  ice-block  the  gravel  sank  and  the 
depressions  appeared. 

The  great  Wenham  swamp,  in  the  towns  of  Wenham  and  Hamilton, 
an  area  of  some  two  thousand  acres,  was  formerly  occupied  by  a  large 
ice-block,  which  extended  northward  into  Topsfield.  At  the  south  and 
east  is  the  overwash  sand-plain,  across  which  Cherry  and  Arbor  streets 
extend.  Around  Muddy  pond  and  Pleasant  pond  the  contact  assumes 
the  form  of  cones  and  short  ridges,  with  steep  sides  dipping  into  the  swamp. 
On  either  side  of  Arbor  street  are  "kettle  holes"  all  having  small  tarns 
at  the  bottom.  (See  Figs.  i6i,  162.)  The  sand-plain  extends  south- 
easterly across  Wenham  and  into  North  Beverly,  and  on  the  east  it  covers 
the  larger. part  of  the  town  of  Hamilton.  From  Cherry  street,  in  Wen- 
ham, to  Mapleville,  West  Wenham,  the  gravel  ridge  on  the  shore  of  the 
swamp  is  continuous  for  about  a  mile,  and  everywhere  throughout  its 
length,  exhibits  the  varying  slope  of  the  ice-contact,  and,  at  the  outer 
end  of  the  swamp,  knob  and  basin  topography. 

Cedar  pond,  in  Wenham,  a  small  ice-block  hole,,  is  surrounded  by 
overwash  gravels  in  cones  and  short  ridges  reaching  to  the  shore  of  Wen- 
ham lake.  On  Enon  street,  in  North  Beverly,  the  steep-sided  ridge 
sloping  down  to  the  lake,  marks  with  great  distinctness,  the  ice-contact  with 
its  overwash  plain,  which  extends  across  North  Beverly  to  the  seashore. 

The  ice-block  which  formed  Wenham  lake  was  probably  continuous 
in  the  valley  now  occupied  by  the  Miles  river,  the  outlet  of  the  lake,  and 
extended  to  the  Longham  basin  and  East  Wenham.  (See  Fig.  165.) 
This  contact  in  the  Longham  region  is  peculiar,  in  that  the  ice  occupied 
a  comparatively  narrow  area,  and  must  have  extended  southeasterly 
for  over  a  mile,  forming  on  both  sides  fine  examples  of  overwash  ridges, 

forming  around  its  borders,  is  situated  in  Salem  near  the  Salem  and  Swampscott  town 
line  and  southwest  from  the  summit  of  Legg's  hill.  (See  Fig.  159.)  Crooked  pond,  Box- 
ford,  is  an  ice-block  hole  now  represented  by  two  small  ponds.  This  pond  is  fast  disap- 
pearing, having  been  reduced  in  area  more  than  one  half  during  the  past  one  hundred 
years  by  the  growth  of  vegetable  matter.  Sphagum  moss  grows  very  rapidly  at  the 
water's  edge  and  reaching  out  into  the  pond  offers  a  resting  place  for  wind-blown  soil,  in 
which  marsh  plants  soon  obtain  a  foothold,  and  in  a  few  years  swamp-bushes  and  trees 
commence  to  grow  and  form  a  strong  network  of  roots  upon  the  surface  of  the  pond, 
which  may  be  walked  upon  with  perfect  safety.  These  ingrowing  swamps  formed  over 
the  surfaces  of  ponds  have  been  called  "quaking  bogs,"  from  the  tremulous  wave-like 
motion  produced  when  they  are  walked  upon.     (See  Fig.  160.) 


Fig.    145.  — HOG    ISLAND,    ESSEX,    AT    LOW  TIDE. 
A  typical  drumlin  showing  adolescent  grass-grown  scarps  caused  by  land-slide 


Fig.    146.— MUSSEY   HILL,    ROWLEY. 
en  from  the  rolling  sand-plain  towards  the  southwest. 


Fig,    147.  — OLD    TOWN    HILL,    NEWBURY. 
View  from  the  southwest  across  the  tidal    marsh. 


Fig.    148.— EAGLE    HILL,    IPSWICH. 
A  small   drumlin,  with   base  cut  by  wave-actic 


KAMES    AND    ICE-BLOCK    HOLES  289 

-or  kame  terraces,  with  characteristic  knobs  and  basins,  sloping  to  the 
contact  with  the  ice  in  the  valley.  Northwest  of  the  main  area  of  Wen- 
ham  swamp  there  is  a  smaller  swamp  known  as  Leach's  swamp,  on  the 
southeastern  extension  of  which  is  built  a  sandy  gravel-plain,  over  which 
Wenham  street  is  constructed  for  the  distance  of  about  three  hundred 
yards.  The  easterly  part  of  this  street  is  built  upon  the  edge  of  a  sharp 
bank  which  is  an  ice-contact,  somewhat  circular  in  outline,  that  develops 
into  a  sharp  ridge  (see  Figs.  163,  164)  on  the  edge  of  the  swamp  for  about 
two  hundred  yards,  and  without  doubt,  marks  an  extension  of  the  con- 
tact into  the  swamp.  A  considerable  plain  of  coarse  gravel  extends  from 
this  contact,  and  is  succeeded  by  one  composed  of  fine  sand,  one  half  a 
mile  further  to  the  southeast. 

In  the  Wenham  swamp  area,  there  are  several  islands  of  fine  sand. 
When  the  ice-block  that  occupied  this  area  became  very  old,  these  sands 
were  probably  washed  into  large  holes  in  the  ice,  from  the  surface  of  over- 
wash  gravels.  One  of  these,  Turkey  island,  is  the  remnant  of  a  drumlin, 
and  is  composed  of  boulder-till.  Its  low,  flat,  upper  surface  is  covered 
by  a  thin  sheet  of  water-laid  sand  and  gravel,  and  at  the  northern  edge 
it  is  very  steep,  and  probably  jnarks  an  ice-contact. 

At  the  south  of  Wenham  swamp,  across  Asbury  Grove  and  Wenham, 
the  outwash  gravels  join  the  gravels  of  the  great  wash-plain  which  covers 
nearly  the  whole  area  of  Wenham  and  Hamilton.  Cutler's  pond,  in  Ham- 
ilton, is  probably  the  eastern  extension  of  the  ice-block  of  this  area. 

The  wash-plain  gravels  which  cover  the  region  known  as  the  "back 
side  of  Hamilton,"  and  also  part  of  Ipswich,  show  ice-contacts  on  the 
northern  bank  of  the  Ipswich  river  from  Mile  brook  in  Topsfield  to  Miles 
river,  the  outlet  of  Wenham  pond.  The  present  bed  of  the  Ipswich  river, 
therefore,  was  the  front  of  the  retreating  ice-sheet  in  this  region  when 
this  sand-plain  was  deposited.  At  the  north  of  Dummer's  hill,  between 
Bartholomew's  hiU,  Scott's  hill,  and  Bush  hill.  Bull  brook  takes  its  rise  in 
Pine  swamp.  Probably  local  glacial  ice  formed  here  the  kame  topography 
of  short  ridges,  cones,  and  sand-plains  which  extend  southeasterly  to 
the  Ipswich  river. 

Near  MiU  river  in  Rowley  and  Georgetown,  at  the  west  of  the  Ipswich 
area,  is  a  noted  region  for  kames,  knobs,  and  basins.  In  Georgetown,  from ' 
Long  hill  to  Redshank  hill,  the  longer  axes  of  these  kames  are  generally 
in  a  northeasterly  to  southwesterly  direction,  and  across  the  line  of  gla- 
•ciation  of  this  region.  The  outward  sand-plain  at  the  southeast,  extend- 
ing across  Rooty  plain  and  Linebrook  parish,  to  Topsfield,  is  the  work 


290  KAMES    AND    ICE-BLOCK   HOLES 

of  overwash  and  outwash  gravels,  to  be  expected  in  front  of  an  ice- 
contact.  "Kettle  holes"  are  seen  in  many  parts  of  this  area,  and  many 
of  the  larger  individual  holes  have  well  developed  overlapping  sand  and 
gravel  outwash  on  top  of  the  general  sand-plain.  Some  of  these  ice- 
block  holes  are  of  remarkable  depth,  with  very  steep  sides.  One  is 
situated  about  half  a  mile  north  of  the  Boxford,  Georgetown,  and 
Rowley,  town  boundary  lines,  on  the  division  line  between  Georgetown 
and  Rowley.  Others  occur  south  of  Mill  river  on  the  Rowley  and  Box- 
ford  boundary  lines.  There  are  several  remarkable  "kettle  holes"  in 
Linebrook  parish,  and  between  Howlett's  brook  and  Mile  brook  in  Tops- 
field,  there  is  one  that  is  forty  feet  deep.  On  the  John  W.  Perkins  farm 
in  Topsfield,  near  Mile  brook,  is  a  series  of  remarkable  kame  terraces 
with  very  steep  sides,  extending  in  a  westerly  direction.  These  terraces 
are  the  ridges  which  were  left,  after  the  berg-ice  in  front  of  the  large  ice- 
block  at  Hood's  pond  had  melted.  The  steep  banks  of  gravel  and  sand 
on  the  southerly  shore  of  this  pond  are  excellent  examples  of  ice-contacts, 
exhibiting  the  accompanying  flood-plain  of  sand  and  gravel  at  the  south- 
east, extending  across  Topsfield. 

The  Chebacco  lakes  in  Essex,  Hamilton,  and  Wenham,  are  also  ice- 
block  holes,  with  outward  overwash  sand-plains,  short  gravel  ridges, 
cones,  and  berg-ice  holes  deposited  in  a  south  to  southwesterly  direction. 
Knowlton's  swamp,  from  Hamilton  Four  Comers  and  parallel  to  Eastern 
avenue  in  Hamilton,  is  a  typical  ice-contact  of  water-laid  sand  and  gravel, 
sloping  abruptly  to  the  low  ground  of  the  swamp.  It  is  over  one  half 
a  mile  long.  The  wash-plain  of  gravel  and  sand  deposited  outward 
along  this  ice-front;  the  short  kame-like  ridges,  cones,  and  lobate  fans 
of  sand  fringing  outward  and  inclosing  areas  around  Beck's  pond;  the 
sand-plain  at  Woodbury's  Station  on  the  Boston  and  Maine  railroad; 
and  Beech  plain  in  the  Hamilton  and  Essex  woods,  all  are  portions  of 
the  wash-plain  extending  from  Knowlton's  swamp. 

Bound  pond,  Gravelly  pond,  and  Coy's  pond,  in  Hamilton  and  Wenham, 
are  also  ice-block  holes  having  contacts  of  sand  and  gravel  on  their  south- 
easterly shores  that  develop  outward  into  sand-plains  and  kames,  filling 
a  large  part  of  the  lowlands  between  the  outcropping  granite  ledges.  At 
Essex  and  Manchester,  among  the  granite  hills,  there  are  numerous  short 
drainage-creases  usually  extending  in  directions  east  or  west  of  the  line  of 
glaciation,  where  water  from  the  melting  ice,  in  its  final  retreat  from  the 
region,  washed  out  the  till,  sand,  and  gravel,  leaving  these  creases  filled 
with  rocks  and  boulders.     (See  Fig.  i66.) 


Fig.    149.  — HOG    ISLAND,    ESSEX,    AT    HIGH    TIDE. 
The  rocks  in  the  foreground  are  the  remnants  of  a  stone  wall  on  either  side  of  a  road  which   has    been  subn^ 
because  of  subsidence. 


Fig.    150.— GREAT   HILL,    HAVERHILL,    AS    SEEN    FROM    WHITTIER'S    HILL. 


Fig,    151.— DRUMLINS    ON    JEFFREY'S    NECK,    IPSWICH. 
As  seen  from   Eagle  hill. 


Fig.    152.  — TURKEY    HILL,    A    DRUMLIN    AT    EAST    HAVERHILL. 


POST-PLEISTOCENE    SAND    AND    GRAVEL  295 

The  sand-plain  extending  southeasterly  from  Prospect  hill  in  Rowley 
and  across  Ipswich,  is  formed  in  front  of  an  ice-block  hole  in  Pine  swamp. 
The  outwash  sand-plains  and  kame  ridge  at  the  southeast  of  the  Metcalf 
rock  diorite  outcrop,  form  a  nearly  complete  circle  with  a  gravel  cone  in 
the  center.  Bull  brook  and  its  tributaries,  in  Post-Pleistocene  times,  cut 
down  and  removed  to  clayey  boulder-till  the  sand-plain  in  the  valley. 
Beyond  these  valleys,  sand  and  gravel  ridges  and  rolling  sand-plains  extend 
southeasterly  to  the  Ipswich  river.     (See  Fig   146.) 

Post-Pleistocene  Sand  and  Gravel.  —  South  of  the  village  of  Ipswich, 
fringing  out  in  fan-shaped  lobes  from  Heartbreak  hill,  and  extending  to  the 
northeastern  part  of  the  town  of  Essex,  is  an  area  showing  boulder-till 
ground  moraine,  surrounding  ridges  and  plains  of  sand  deposited  during 
the  Champlain  period. 

In  the  Newbury-Byfield  district,  a  boulder  train  extends  from  the  salt 
marsh  at  the  west  of  Kent's  island,  across  Byfield  to  Georgetown,  a  dis- 
tance of  six  miles  in  a  straight  line,  but  following  an  irregular  course  of  over 
ten  miles.  The  trend  of  the  boulders  is  from  the  northeast  to  the  south- 
west and  marks  a  halting  place  of  the  glacial  ice  in  its  retreat  northward. 
These  boulders  rest  upon  the  surface  of  the  ground  moraine  of  boulder-till 
and  probably  were  once  covered  wholly,  or  in  part,  by  the  sand,  gravel, 
and  clay  that  have  been  washed  southward  during  interglacial  times, 
when  the  land  surface  was  submerged,  and  now  form  the  plain  known  as 
"the  Rye  field"  on  which  the  car  houses  of  the  Boston  and  Northern 
Electric  railroad  are  built.  A  cross-section  through  this  sand-plain  shows 
the  surface  for  a  depth  of  two  feet,  to  be  composed  of  fine  sand  and  silt, 
probably  deposited  in  shallow  water ;  below  this  appears  four  feet  of  coarse 
sand  and  next  is  found  a  deposit  of  very  coarse  gravel  and  well-rounded 
stones  with  no  sand  —  a  typical  sea  beach  or  old  lagoon.  Surrounding 
this  ancient  lagoon,  at  the  south  and  east,  and  extending  westerly  from 
the  South  Byfield  meeting-house,  there  is  a  series  of  sand-dunes,  more  or 
less  grass-grown,  only  to  be  compared  with  the  Post-Pleistocene  dunes  in 
process  of  formation  at  the  present  time  at  Ipswich.  This  plain  covers  an 
area  about  a  mile  square  and  is  from  six  to  ten  miles  inland  from  Plum 
Island  river.  Near  Mill  river  in  Rowley,  and  south  of  this  plain,  beds 
of  clay  and  fine  sediment  are  deposited,  occupying  the  entire  area  to  the 
Newburyport  turnpike  at  Chaplinville. 

The  live  sand-dunes  in  "the  Rye  field"  locality  are  the  finest  examples 
of  inland  sand-dunes  to  be  found  in  the  County.  They  encircle  a  lagoon 
through  which  meanders  Wheeler's  brook,  probably  a  tide-water  creek,  at 


296  POST-PLEISTOCENE    SAND    AND    GRAVEL 

the  time  the  dunes  were  forming.  Many  of  these  sand-dimes  are  grass- 
grown  and  in  places  are  covered  with  forest  trees  and  bushes.  They  are 
undoubtedly  of  Pleistocene  age  and  were  formed  during  the  Terrace 
or  late  Champlain  period.     (See  Figs.  167,  168.) 

The  northern  and  western  sides  of  Town  hill,  in  Ipswich,  are  sur- 
rounded by  grass-grown  sand-dunes  and  westerly  from  the  dunes,  cover- 
ing the  Ipswich  poorfarm,  there  is  a  sand  and  gravel  plain  of  considerable 
extent  on  which  is  located  Brown's  brick  clay-pit.  This  plain,  underlaid 
by  clay,  is  comparable  only  with  the  sea-water  lagoons  or  tidal  marshes- 
lying  easterly  from  Town  hill  at  the  present  day.  A  series  of  these  fringes 
of  grass-grown  sand-dunes,  with  lagoons  west  of  them,  may  be  traced 
across  the  whole  County  and  are  undoubtedly  phenomena  of  the  Terrace 
epoch.  Such  a  formation  exists  at  Topsfield  near  the  junction :  of  Fish 
brook  and  the  Rowley  Bridge  road.  Westerly  from  these  dunes,  small 
lagoons,  now  swamps  overgrown  with  larches,  extend  into  Boxford.  The 
sand-  and  gravel-plain  in  this  direction  is  on  both  sides  of  Fish  brook  and 
covers  an  area  about  two  miles  square.  Sand-dunes  are  also  to  be  seen 
east  of  Pentucket  pond  and  Rock  pond  in  Georgetown.  These  dunes- 
extend  in  a  circle  to  South  Groveland  where  the  old  lagoon  to  the  west- 
ward is  very  pronounced  and  easily  traced  over  the  entire  area.  Other 
grass-grown  dunes  are  found  in  Andover  and  Lawrence. 

The  Merrimac  river  was  probably  a  halting  place  of  the  glacial  ice  in 
its  retreat  northward,  for  its  southern  shore,  from  the  mouth  of  the  Parker 
river  to  Pipe  Stave  hill,  marks  typical  ice-contacts  of  morainal-till  and 
overwash  gravels  capped  by  sand  and  silt.  High  street,  in  Newbury  and 
Newburyport,  is  laid  out  upon  the  top  of  the  terrace  formed  by  this- 
ice-contact,  a  section  of  which  shows  it  to  be  composed  of  boulder-till  and 
clay-beds  resting  upon  the  glaciated  bed-rock  of  quartz  augite  diorite  in 
varying  depths.  At  Grasshopper  plain  it  is  at  least  fifty  feet  in  thickness, 
and  is  covered  by  twenty  feet  of  coarse  gravel  with  twenty-five  feet  of 
fine  sand  at  the  surface.  This  fine  sand  is  creased  by  a  number  of  steep- 
sided  valleys  or  drainage-creases  extending  in  a  southerly  direction  to  the 
Little  river  clay-beds  in  Newbury.  A  section  of  this  terrace  across  High 
street  (see  Fig.  169),  extending  from  the  river  through  Green  street  to  the 
frog  pond  by  "the  Mall,"  gives  boulder-till  on  High  street  at  an  elevation 
of  eighty  feet  above  tide  water.  The  frog  pond  is  the  site  of  a  small  de- 
tached iceberg  that  was  buried  in  the  morainal-till.  South  of  "the  Mall,"' 
the  overwash  and  outwash  gravels  have  formed  a  series  of  cones  and 
short  ridges  or  kames  of  sand  and  gravel  extending  southeasterly  into 


iL^TS^S^^^fcat-  — 


Fig,    153,— WHITTIER'S    HILL,    A   DRUMLIN    AT    HAVERHILL, 


Fig.    154.  — ICEBERG    OR    KETTLE    HOLE    IN    THE    "DUNGEONS." 
Marblehead. 


155.  — ICEBERG    HOLES    IN    KAME   GRAVELS    NEAR    LEGG'S    HILL,    SOUTH    SALEM. 
Legg's  hill,  a  wave-swept  outcrop  of  hornblende  diorlte,  nnay  be  seen  In  the  distance. 


Fig.    156.  — ICEBERG    HOLE    IN    OVER-WASH    GRAVELS. 
lowing  a  short  kame  within  the  hole.     The   "dungeons,"    Marblehcad. 


POST-PLEISTOCENE    SAND    AND    GRAVEL  301 

Newbury.  The  tracks  of  the  Boston  and  Maine  railroad  cut  through  these 
gravels  on  the  west,  and  the  track  of  the  City  Freight  railroad  cuts  through 
them  on  the  east.  In  1898,  this  cut  exhibited  a  good  section  of  the  depos- 
its some  three  htmdred  yards  in  length.  The  gravels  and  sands  dipped  to 
the  south  at  an  angle  of  35°  and  were  capped  by  a  deposit  of  clay  having 
sand  partings  every  few  inches.  The  greatest  depth  of  the  gravel  and 
sand  was  forty  feet.  North  of  the  center  of  the  hill  there  was  a  dip  twenty 
feet  deep  filled  with  clay  having  fine  sand  partings,  and  under  the  clay, 
at  the  bottom  of  the  dip,  there  was  a  mass  of  peat,  probably  the  site  of 
an  iceberg  in  the  gravel  before  the  clay  was  deposited. 

South  of  Oak  Hill  Cemetery  there  is  a  "kettle  hole"  which  a  few  years 
ago  contained  a  floating  island.^  In  the  spring  of  the  year  when  the  melt- 
ing snows  raise  the  water  level,  this  pond  covers  an  area  of  about  a  quarter 
of  an  acre.  It  is  a  typical  small  ice-block  hole  with  southeastern  out- 
wash  sand  and  gravel  kames  probably  deposited  in  cracks  or  gorges  in 
the  glacial  ice  which  filled  the  whole  valley  of  Little  river. 

High  street,  in  Newbury,  is  built  on  sand  and  gravel  that  cap  clay 
and  till,  a  typical  beach  barrier  sloping  back  to  the  lagoon  at  Four  Rock 
creek.  The  debris  is  washed  away  from  the  outcropping  ledges  that 
rise  above  the  boulder-till  covering  the  surface.  This  beach  barrier  with 
the  lagoon  on  the  shore  side  occupied  the  whole  of  the  Little  River  valley 
and  was  continuous  on  the  southwest  around  Old  Town,  and  Little  Old 
Town  hills.  A  gorge  between  these  hills,  now  filled  with  coarse  water- 
worn  gravels  on  top  of  boulder-till,  was  the  drainage  outlet  to  the  south- 
east. In  front  of  the  gravels,  the  outwash  sands  spread  out  over  Newbury 
Old  Town,  to  the  mouth  of  Parker  river  where  steep  banks  and  fringing 
lobes  extend  into  the  salt  marsh  overlapping  the  boulder-till. 

Eagle  hill,  on  Kent's  island,  in  Newbury,  is  composed  of  slate  rock, 
well  glaciated,  polished,  and  scratched  with  fine  strise.  On  the  north 
side  of  the  hill,  in  the  shallow  bed  of  Little  river,  and  only  to  be  seen  at 
very  low  tide,  is  the  longest  and  deepest  glacial  groove  known  to  exist 
in  Essex  County,  and  probably  in  New  England.  This  groove  is  cut 
southeast  and  northwest  in  a  slate  and  sandstone,  somewhat  metamor- 
phosed into  a  hard  rock,  and  is  eighteen  inches  wide,  six  inches  deep, 
and  forty  feet  long.  Sections  of  it,  extending  towards  the  southeast, 
may  be  traced  for  nearly  five  hundred  yards  along  the  shore  of  the  island, 
after  it  leaves  the  bed  of  Little  river.  Another  deep  groove  occurs  on 
the  east  side  of  Green  street,  Newbury  Old  Town,  near  the  comer  of  Han- 

'  See  American  Journal  of  Science  (1827),  VoL  XII,  p.  122. 


302  POST-PLEISTOCENE    SAND    AND   GRAVEL 

over  street.  It  is  cut  in  a  quartz  diorite  ledge,  and  is  eight  inches  deep, 
twenty-eight  inches  wide,  and  thirty  feet  long.     (See  Fig.  170.) 

A  well-marked  ice-contact,  showing  a  halting  place  in  the  retreat  of 
the  ice,  was  formed  in  what  is  now  Hampton  Falls  river  in  New  Hamp- 
shire. From  this  contact,  all  the  glacial  gravels  with  berg  and  small  ice- 
block  holes  may  be  traced  across  Amesbury  and  Salisbury.  (See  Fig. 
172.)  A  swamp  between  South  Seabrook  and  Salisbury  shows  a  good 
ice-contact  on  the  southern  edge,  with  overwash  and  outwash  kames 
and  sand-plains  extending  across  East  Salisbury  and  thinning  out  near 
the  salt  marsh.  East  Salisbury  is  a  typical  sand-plain,  with  ntunerous 
sand-dunes  marking  a  former  iseach  barrier. 

In  Pelham,  Windham,  Salem,  Atkinson,  Kingston,  and  Newton,  New 
Hampshire,  towns  joining  Essex  County  on  the  north,  a  series  of  ponds, 
whose  trend  is  from  the  northeast  to  the  southwest,  were  sites  of  masses 
of  glacial  ice,  and  the  waters  formed  from  the  melting  of  these  great 
bodies  of  ice,  drained  southward  and  carried  sand  and  gravel  across  the 
whole  area  of  these  towns  and  filled  the  valleys  between  the  drumlins 
in  Essex  County,  north  of  the  Merrimac  river. 

Kimball's  pond,  in  the  towns  of  Amesbury  and  Merrimac,  is  an  ice- 
block  hole  where  a  large  mass  of  ice  was  partially  buried  by  drift  gravel 
and  sand  from  the  drainage  in  front  of  the  retreating  ice  in  New  Hamp- 
shire. On  the  southeastern  shore  of  the  pond  there  is  a  remnant  of  an 
ice-contact  composed  of  bouldery  gravels  with  outwash  sand  covering 
the  east  side  of  Pond  hill  and  the  western  part  of  Amesbury,  and  having 
kames  which  expand  into  sand-plains,  cones,  and  terraces  of  gravel.  An 
ice-contact  was  formed  in  the  Powow  River  valley,  south  of  Ring's  hill 
in  Amesbury,  where  moraines  of  till  and  kame  terraces  of  sand  and  gravel 
cover  the  region.  Captain's  pond,  in  Salem,  New  Hampshire,  is  the  site 
of  a  block  of  glacial  ice  with  a  southeasterly  contact.  A  moraine  of 
clayey  sand  and  gravel  forms  the  shore  of  the  pond  and  outwash  gravels 
and  sand  fill  the  valley  between  Ayer's  hill,  in  Haverhill,  and  Spicket 
hill  in  Salem,  New  Hampshire,  and  extends  southward  on  both  sides  of 
Hawkes'  brook  in  Methuen  to  the  Merrimac  river.  The  Spicket  river 
during  its  southwesterly  course  from  Spicket  hill  in  Salem,  New  Hamp- 
shire, to  the  town  of  Methuen,  occupies  the  site  of  a  former  ice-contact, 
for  the  present  river  valley  would  have  been  parallel  to  the  front  of  the 
retreating  glacial  ice.  The  present  course  of  the  Spicket  river  in  Methuen 
and  Lawrence,  is  probably  in  a  drainage-crease  which  ran  from  the  front 
of  the  glacial  ice  when  it  occupied  this  area.     Kames  and  ridges  which 


Fig.    157.  — OVER-WASH    GRAVELS,    ICEBERG    HOLES,    AND    SHORT    RETICULATED    KAMES. 
V/inter  scene   at  the    "  Dungeons,"    Marblehead.      Legg's   hill    at  the   left. 


^^5^'^g!<???'^^^^^^^ 


Fig.    I  58.— Vi'lNTER    SCENE    AT    THE    "DUNGEONS,"    MARBLEHEAD. 
Legg's   hill    at   the   right. 


I.— LEGG'S    HILL    POND,    SALEM, 
e-block   hole   nearly   filled    by  peat. 


Fig.    160.  — CROOKED    POND,    BOXFORD. 
h   has  become  a   nearly  filled    pond.      Bald   hill 


in  the  distance. 


POST-PLEISTOCENE    SAND    AND    GRAVEL  307 

expand  into  lobate  sand-plains,  and  cones  resting  upon  boulder-till,  cover 
the  town  of  Methuen  on  both  sides  of  the  Spicket  river,  extending  across 
Lawrence  and  South  Lawrence  into  North  Andover.  A  boulder-train 
or  terminal-moraine  in  the  southwestern  part  of  Methuen,  half  a  mile 
east  from  the  Dracut  boundary,  marks  a  halting  place  of  the  glacier. 
The  drainage  from  the  front  of  this  moraine  must  have  followed  the  pres- 
ent course  of  the  Merrimac  river,  as  across  the  river  in  the  western  part 
of  the  town  of  Andover,  the  whole  surface  of  the  region  from  Wood  hill 
to  South  Lawrence  is  covered  by  boulder-till.  From  Wood  hill  to  East 
Lawrence  fine  sand  and  river  silt  occur  on  each  side  of  the  river  in  a 
belt  one  eighth  of  a  mile  wide,  and  a  thin  coating  of  this  deposit  covers 
the  boulder-till  in  parts  of  the  area  across  West  Andover.  Upper-till, 
composed  of  clayey  sand  and  gravel  with  numerous  boulders,  some  of 
which  are  of  great  size,  may  be  seen  in  all  the  railroad  cuttings,  especially 
along  the  Lowell  and  Lawrence  branch  of  the  Boston  and  Maine  rail- 
road. These  boulders  were  deposited  from  the  lower  part  of  ice-floes, 
when  the  area  was  submerged  below  the  surface  of  the  sea,  the  water  after- 
wards washing  out  most  of  the  clay  and  leaving  the  sand,  gravel,  and 
boulders  as  found  to-day. 

A  large  part  of  the  present  surface  of  Andover  owes  its  sculpture  to 
the  cutting  of  stream-valleys  in  glacial  sand-plains,  thereby  leaving  residual 
ridges.  Many  of  these  valleys  are  paved  with  well-rounded  stones  and 
boulders.  An  excellent  example  of  these  ridges  may  be  seen  along  the 
line  of  Lowell  street  between  Hackett's  pond  and  Frye's  Village  in  West 
Andover. 

Lake  Cochichewick  in  North  Andover,  formerly  known  as  Great  pond, 
is  the  site  of  a  large  ice-block  that  probably  extended  across  the  Merrimac 
river.  The  lake  seems  to  have  been  ploughed  out  during  an  advance 
of  the  ice  as  indicated  by  its  depth  below  the  surrounding  land  surface. 
Overwash  gravels  and  moraines  of  boulders  with  drainage-creases  ex- 
tend from  the  lake  towards  the  south  and  southeast,  proving  that  its 
drainage  was  in  that  direction  during  the  melting  of  the  ice  to  the  present 
level  of  the  lake.  These  drainage-creases  occur  on  both  sides  of  Bear 
hill  and  lead  down  to  the  great  sand-plain  which  covers  the  valley  between 
Mill's  hill  and  Bear  hill.  The  area  between  Marble  Ridge  station  and 
Ingall's  station,  on  the  Boston  and  Maine  railroad,  and  the  valley  of 
Boston  brook,  in  Middleton,  and  extending  to  Fish  brook  in  Boxford  on 
the  east,  is  covered  with  short  terraces,  probably  old  sea  beaches,  which 
coalesce  with  sand-plains,   having  grassed-over  sand-dunes.      When  the 


308  POST-PLEISTOCENE    SAND    AND    GRAVEL 

water  in.  Lake  Cochichewick  subsided  to  its  present  level,  the  southern 
outlet,  over  the  granite  ridge,  had  become  dammed  up  by  till  and  the 
stream  running  from  the  lake  was  forced  to  turn  northward,  and  cut  its 
present  channel  through  the  drift-sand  to  the  Merrimac  river. 

Johnson's  pond  and  Chadwick's  pond,  in  Groveland  and  Boxford,  are 
similarly  situated.  The  glacial  drainage  was  easterly  across  South  Grove- 
land  and  the  northern  part  of  Georgetown,  and  sand  and  coarse  gravel 
ridges  cover  the  entire  region.  The  tracks  of  the  Haverhill  and  George- 
town electric  railway  are  laid  on  a  sand  and  gravel  terrace,  which  in 
some  parts  of  the  area  exhibits  a  remarkable  kame  topography.  One 
especially  good  example  is  to  be  seen  in  the  region  known  as  "  Federal 
City,"  where  short  kame-like  ridges,  alluvial  cones  and  "kettle  holes" 
are  features  of  the  landscape.  Uptack  hill,  in  Groveland  and  Boxford, 
a  nearly  bare  ridge  of  Cambrian  rocks,  three  miles  in  length,  and  having 
an  elevation  of  two  hundred  and  forty  feet  in  Boxford,  southeast  of  John- 
son pond,  cuts  off  the  natural  drainage  to  the  southeast  and  forces  the 
streams  in  this  area  northward  to  the  Merrimac,  through  the  fissile  and 
softer  slate  and  sandstone  rocks.  Chadwick's  pond  was  probably  a 
deeply  sunken  ice-block  attached  to  the  larger  block  that  occupied  the 
site  of  Johnson's  pond.  Its  southeasterly  drainage  into  Johnson's  pond 
shows  no  special  features  of  overwash  or  outwash  gravels,  but  toward 
the  northeast  overwash  gravels  fill  the  valley  between  Dead  hill  in  Grove- 
land and  a  low  drumlin  to  the  north  in  Bradford.  These  overwashed 
gravels  cover  the  boulder-till  in  low  rolling  surfaces  and  short  ridges 
as  if,  in  the  glacial  period,  there  had  been  a  drainage  from  this  pond  into 
the  Merrimac  river,  at  Bradford.  Little  Niagara  brook  in  Bradford  fol- 
lows this  course. 

The  southern  side  of  the  Merrimac  river  from  opposite  Hale's  island 
to  Groveland  bridge,  shows  a  nearly  continuous  ice-contact  with  steep 
ridge-like  banks  of  morainal  clay  and  gravel  capped  by  fine  overwash 
sands  which  extend  parallel  to  the  river  for  a  distance  of  about  one  mile, 
to  Argilla  brook,  the  outlet  of  Johnson's  pond.  The  valley  occupied 
by  Argilla  brook,  was  a  drainage-crease  in  front  of  the  glacial  ice.  From 
Bradford,  the  Merrimac  flows  in  a  southeasterly  direction  for  about  two 
miles  to  Argilla  brook,  and  then  bends  and  flows  toward  the  northeast  for 
about  five  miles.  This  bend  in  the  river  was  a  drainage  course  when  the 
waning  ice-sheet  was  less  than  two  hiindred  feet  in  thickness,  and  it  con- 
tinued to  be  a  general  dumping-ground  for  glacial  streams  from  the  north, 
long  after  the  ice  had  retreated  beyond  the  northern  limit  of  the  state. 


Fig.    161.  — ICEBERG    HOLE    IN    AN    OUT-WASH    SAND-PLAIN    EAST    OF    WENHAM    SWAMP. 
Arbor  street,   Wenham. 


Fig.  162.— ICEBERG    HOLE    ON    THE    EAST   SIDE   OF   ARBOR    STREET. 
Wenham. 


•KAME    TERRACE,    MARKING    AN    ICE    CONTACT    ON    THE    SOUTHEASTERN    SHORE    OF 
LEACH'S    SWAMP,    AN   ICE-BLOCK    HOLE. 
West   Wenham. 


Fig.    164.  — ANOTHER    VIEW    OF   THE    ABOVE. 


POST-PLEISTOCENE    SAND    AND    GRAVEL  313 

(See  Fig.  171.)  On  the  south  side  of  the  Merrrmac,  Hutchings'  hill,  in 
Groveland,  and  Brake  hill  and  Farm  hill,  in  West  Newbury,  show  at 
their  bases  and  up  their  sides  to  the  one  hundred  foot  contour  lines, 
old  beach  shore-lines  of  clay,  sand,  and  gravel.  As  these  hills  have  an 
elevation  of  over  two  hundred  feet,  when  the  glacial  ice-front  had 
melted  to  a  thickness  of  less  than  two  hundred  feet,  its  drainage  would 
necessarily  have  been  in  the  valleys  between  the  hills  and  its  deposits 
would  have  been  dropped  according  to  the  size  and  weight  of  the  mate- 
rial, the  coarse  sand  and  gravel  near  the  river,  fine  sand  next,  and  the  clay 
beyond.  This  is  precisely  what  is  found  in  the  area  south  and  southeast 
of  Groveland  bridge.  Karnes  of  coarse  gravel  extend  from  the  river  to  the 
railroad  station,  and  are  succeeded  by  sand  stretching  to  Pine  hill  and 
appearing  on  both  sides  of  the  railroad  track  until  the  Georgetown  boun- 
dary line  is  reached. 

Cheney's  hill,  in  Groveland,  on  the  bank  of  the  Merrimac,  formerly 
was  composed  entirely  of  boulder-till.  This  was  cut  down  nearly  to  the 
level  of  the  river,  and  afterwards  built  up  by  overwash  sand  and  graveJ. 
The  sand-plain  extends  toward  the  north  and  is  now  occupied  by  a  ceme- 
tery, where  Palmer's  creek  cuts  down  through  the  sand  to  boulder-till 
and  clay  at  the  level  of  the  river.  Round  pond,  Kenoza  lake,  and  Lake 
Saltonstall,  all  in  Haverhill,  are  sites  of  glacial  ice-blocks  and  are  sur- 
rounded by  drumlins  and  overwash  gravels  on  their  southeastern  shores. 
Overwash  gravels  form  the  sand-plain  at  "Riverside,"  and  on  both  sides 
of  Argilla  brook  extending  up  on  Huckleberry  hill  and  down  to  the  Merri- 
mac. River  silts  of  Post-Pleistocene  age  form  the  banks  of  the  river  on 
the  north  (see  Fig.  173),  and  on  the  south  it  has  a  tendency  to  cut  down 
its  bank  as  it  flows  by  Bradford,  Groveland,  and  West  Newbury. 

Creek  pond,  or  Crystal  lake,  in  North  Haverhill,  is  situated  in  a  rock- 
bound  basin  surrounded  by  micaceous  granite.  Creek  brook,  its  outlet, 
flows  southeasterly  and  was  probably  the  drainage  outlet  from  this  pond 
when  it  was  occupied  by  glacial  ice.  Outwash  sands  and  gravels  extend 
towards  the  south  on  both  sides  of  the  brook  as  far  as  West  Meadow  hill, 
and  also  to  the  base  of  Silver  hill  and  to  the  banks  of  the  Merrimac. 

South  of  Uptack  hill,  the  Parker  river  flows  across  Boxford  and  George- 
town to  Rock  pond,  a  distance  of  about  three  miles.  The  river  valley  is 
in  a  line  parallel  with  the  front  of  the  glacial  ice,  and  the  usual  overwash 
sand-ridges,  cones,  and  kames  which  expand  to  sand-plains  and  rolling 
sandy  terraces,  are  to  be  seen  its  entire  length.  On  part  of  this  area  the 
exact  line  of  contact  has  been  cut  away  by  Post-Pleistocene  erosion. 


314  POST-PLEISTOCENE    SAND    AND    GRAVEL 

The  ice-front  when  it  occupied  this  valley  must  have  been  over  two  hun- 
dred feet  in  thickness,  for  overwash  gravels  and  moraines  of  boulders  are 
found  above  the  two  hundred  foot  contour  line  on  Stiles'  hill  and  Spof- 
ford's  hill  in  Boxford,  and  Bald  Pate  hill  in  Georgetown.  Bald  Pate  hill 
is  a  typical  drumlin  in  which  a  channel  has  been  cut  by  a  landslide  and 
boulders  from  the  boulder-till  have  been  pushed  forward  and  down  its 
southeastern  slope.  This  channel,  or  valley,  caused  by  an  ice  advance, 
has  since  been  filled  by  overwash  gravels  from  the  contact  in  the  Parker 
River  valley.  During  the  final  retreat  of  the  ice-sheet  from  this  region, 
overwash  gravels  extended  across  Boxford  and  into  Topsfield. 

A  series  of  ponds  in  Boxford  —  Stiles',  Spofford's,  Perley's,  Four 
Mile,  and  Cedar,  are  all  ice-block  holes  showing  contacts  on  their  south- 
eastern shores.  Cedar  Pond  brook  forms  the  Kimball  mill-pond  and,  on 
the  south  side  of  the  road  below  the  pond,  there  is  a  deposit  of  infuso- 
rial earthy  clay  from  one  to  three  feet  in  thickness  and  covering  about 
one  acre  which  is,  without  doubt,  of  glacial  age.  Stevens'  pond,  in  Box- 
ford, is  a  typical  ice-block  hole  where  an  elongated  mass  of  ice  extended 
from  the  large  block  in  the  valley  of  Four  Mile  pond.  The  steep  south- 
eastern shore  of  Stevens'  pond  is  a  fine  example  of  contact,  the  gravel 
and  clay  covering  nearly  one  hundred  acres  at  the  east  of  Stevens'  hill, 
a  low  boulder-till  ridge,  and  extending  southerly  on  both  sides  of  Pye 
brook  as  far  as  Topsfield.  The  surface  of  this  plain  is  composed  of  fine 
quartz,  sand  and  silt  forming  the  soil  of  the  area.  Below  the  surface, 
from  three  to  ten  feet,  the  deposit  is  found  to  be  clear  of  sand  and  com- 
posed of  round  gravel-stones  three  to  six  inches  in  diameter,  each  stone 
as  smooth  as  if  from  a  sea  beach.  Between  Fish  brook  in  Boxford,  and 
Mile  brook  in  Topsfield,  an  area  two  and  one  half  miles  long  and  two 
miles  wide,  the  surface  is  marked  by  short  ridges  and  circular  terraces, 
"kettle  holes,"  and  reticulated  kames.  South  of  Fish  brook,  as  it  flows 
between  Boxford  and  Topsfield,  there  is  an  ancient  sea  beach  with  sand- 
dunes  and  wind-blown  sands  underlaid  by  round  gravels.  These  sea 
beach  deposits  of  sand  and  gravel  formerly  extended  from  this  point  in  a 
southeasterly  direction  to  the  present  seashore,  but  were  largely  removed 
by  wash  of  waters  from  melting  ice-blocks. 

Forest  lake,  in  Middleton,  is  a  basin  in  the  granite  gneiss  rocks 
ploughed  out  by  the  advancing  ice-sheet.  The  shore  at  the  southeast  of 
the  lake  exhibits  no  evidence  that  this  basin  was  formerly  occupied  by 
an  ice-block  as  there  is  no  ice-contact.  Bare  ledges  and  water-washed 
boulders  cover  the  area  extending  southerly  across  the  Ipswich  river  to 


Fig.    165.  — WENHAM    LAKE. 
The  free-covered   point   at  the  left  is  a  gravel  terrace   i 


irking  an  ice  contact. 


"^^^^^■- 


Fig.    166. -DRAINAGE    CREASE   ABOVE    A    LAND-SLIDE    ON    THE    SOUTHWESTERN    SIDE    OF    HOG    ISLAND. 


Fig.    168.  — ANOTHER    VIEW    OF   THE   ABOVE. 


POST-PLEISTOCENE    SAND    AND    GRAVEL  ■  319 

Paper  Mill  hill.  East  of  the  lake,  and  near  the  bank  of  the  Ipswich  river, 
there  is  a  narrow  lagoon  with  grass-grown  sand-dunes  extending  nearly 
to  the  dam  at  the  paper  mill  —  without  doubt,  in  interglacial  times, 
washed  by  the  sea,  in  fact,  an  inland  sea  beach  with  its  fringe  of  sand- 
dunes  on  the  southeast. 

The  Ipswich  River  valley  from  North  Reading  to  Danvers,  shows  evi- 
dence that  it  was  submerged  beneath  the  sea  for  a  long  period  after  the 
retreat  of  the  glacial  ice  from  this  region.  Northward,  across  North 
Reading,  Wilmington,  and  Tewksbury,  to  Lowell,  the  evenly-bedded  sands 
and  gravels  which  cover  the  area  extending  towards  Andover  and  the 
Merrimac  river,  furnish  conclusive  evidence  of  sea-laid  deposits  in  a 
shallow  basin  of  the  ocean.  Sand  and  gravel  terraces  across  this  area 
also  mark  the  ancient  sea  beaches.  Paper  Mill  hill  and  Upton's  hill, 
both  having  an  elevation  of  about  two  hundred  feet,  are  steep-sided 
hills  of  fine  sand,  and  probably  mark  ice-contacts  from  near  their  sum- 
mits. Walden's  hill,  two  miles  to  the  south,  having  an  elevation  of  one 
hundred  and  eighty  feet,  is  composed  of  ordinary  coarse  gravel  with 
ntunerous  large  boulders  upon  the  surface,  probably  dropped  from  the 
bottom  of  floating  ice,  the  sand  and  silt  between  having  been  removed 
by  sea  wave-action  and  washed  towards  West  Peabody,  where  large 
deposits  of  sand  and  gravel  are  found. 

Will's  brook,  in  Lynnfield,  occupies  a  valley  in  a  swamp  one  third 
of  a  mile  wide  and  one  sixth  of  a  mile  long.  This  swamp  was  an  ice- 
block  hole,  an  extension  south  from  the  main  mass  of  ice  in  the  Ipswich 
river  valley.  Outwash  gravel  and  sand  from  this  valley  formed  Pine 
hill  and  covered  the  surface  of  the  whole  area  of  Lynnfield  Centre.  Pil- 
lings'  pond  and  Suntaug  lake  are  sites  where  ice-blocks  were  stranded 
or  where  remnants  of  local  glaciers  remained.  The  ice-contact  on  the 
southern  and  southeastern  shores  of  Suntaug  lake  is  a  remarkably  good 
example,  having  the  steep  slope  of  the  sand  and  gravel  sliding  down  to 
the  shore  of  the  lake.  This  contact  formed  a  terrace  with  an  elevation 
of  forty  feet  above  the  surface  of  the  lake,  and  spreading  out  as  a  sand- 
plain  in  a  southeasterly  direction  for  over  a  mile.  North  of  the  lake  and 
near  the  comer  of  Lake  street  and  the  Newburyport  turnpike,  there  is 
a  ridge  of  granite  boulders,  in  part  resting  on  the  hornblende  granite 
ridge  of  the  region,  probably  eroded  in  situ,  which  were  pushed  forward 
by  the  glacial  ice,  and  deposited  as  a  lateral  moraine,  marking  a  halting 
place  of  the  glacier  in  its  retreat  northward.  These  boulders  are  iden- 
tical in  character  with  the  granite  of  the  Peabody  and  South  Lynnfield 


320  POST-PLEISTOCENE    SAND    AND    GRAVEL 

region,  and.  no  outcrop  of  similar  granite  is  known  in  New  England  in 
the  line  of  glaciation  toward  the  northwest. 

The  peat  swamps  south  of  Phelps'  mills  indicate  ice-block  holes,  and 
the  region  to  the  southeast  is  covered  with  short  terrace-like  ridges,  kames 
which  expand  southward  into  sand-plains,  and  numerous  "kettle  holes" 
which  are  very  intricate  in  outline.  The  sand-plain  occupies  the  region 
known  as  the  "Kingdom"  and  extends  into  West  Peabody. 

The  series  of  crystalline  ridges  of  diorite  and  granite  rocks,  south 
and  southeast  of  Dan  vers,  is  interesting  as  showing  that  drift  boulders 
from  these  outcropping  ridges  of  bed-rock  usually  were  merely  pushed 
forward,  for  boulders  of  the  diorite  rock  from  Hog  hill,  Peabody,  or  from 
Danvers,  rarely  are  found  as  erratics  on  the  granite  areas,  whereas,  on 
the  diorite  areas,  the  boulders  are  invariably  diorite.  That  the  diorite 
boulders  are  nearly  always  angular  with  sharp  comers  is  another  distinc- 
tive feature,  whereas,  the  granite  boulders,  on  the  granite  areas  of  Pea- 
body and  the  Lynn  woods  are  usually  from  subangular  to  well-rounded 
blocks.  Indeed,  concerning  the  boulders  in  these  areas,  the  rule  is  so 
distinctive  that  with  few  exceptions,  the  boulders  on  the  surface  indi- 
cate the  bed-rock  beneath.  Occasionally  erratics  are  found,  however, 
brought  from  a  distance.  Boulders  from  the  Topsfield  red  granite  and 
the  Boxford  foliated  quartz  diorite  are  occasionally  seen  on  the  backs  of 
drumlins,  and  in  the  lower  areas  of  boulder-till  or  hard-pan  in  the  val- 
leys of  the  diorite  areas,  and  an  occasional  boulder  of  the  typical  horn- 
blende granite  from  the  Peabody  area  is  sometimes  found  perched  upon 
the  summit  of  the  diorite  areas  in  the  southeastern  part  of  Peabody, 
in  Salem,  and  on  the  sea-shore  at  Marblehead.  The  ridges  of  granite 
boulders  on  the  granite  areas  in  Peabody  and  in  the  Lynn  woods,  are 
usually  found  to  be  accumulations  of  these  erratic  boulders  resting  on 
the  sides  of  valleys,  and  probably  a  large  part  of  them  are  boulders  of 
erosion  that  have  been  carried  forward  toward  the  southeast  a  short 
distance. 

Ship  rock,  a  large  hornblende  granite  boulder  in  Peabody,  the  pro- 
perty of  the  Essex  Institute,  and  estimated  to  weigh  about  twenty-two 
hundred  tons,  is  perched  upon  a  ledge  at  an  elevation  of  about  one  hun- 
dred feet  above  mean  sea-level.  (See  Fig.  174.)  Across  the  valley,  two- 
thirds  of  a  mile  distant,  in  a  northwesterly  direction,  which  is  the  direc- 
tion of  glaciation  for  this  area,  there  is  a  hornblende  granite  outcropping 
ledge  with  an  elevation  of  two  hundred  and  thirty  feet  above  mean  sea- 
level.     Without  doubt  "Ship  Rock"  was  formerly  a  part  of  this  outcrop. 


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Fig.    169.  — CROSS-SECTION    OF    A    TERRACE    AT    HIGH    STREET,    NEWBURYPORT. 
A.    Sand  and  gravel.     B.    Clay  with   sand  partings.     C.    Peat  deposit. 


Fig.    170.  — GLACIAL  GROOVE    IN    A   QUARTZ    DIORITE    LEDGE  ON   THE    EAST    SIDE  OF  GREEN    STREET. 

Newbury. 


Fig.    171.  — MERRIMAC    RIVER. 
The  bend   below  Mitchell's  falls,   showing  deposits  of  river  silts.     Kame  gravels    in  the  foreground. 


•ENCLOSED    BLOCK  OF    FERRUGINOUS    GRAVEL    PROBABLY    DEPOSITED    IN    A    FROZEN    MASS 
DURING    LATE    GLACIAL   TIMES. 
Sand-plain  east   of  the  railroad  station  at   Hampton,    N.  H. 


,j.ti^^t0W^^^    - 


Fig.    173.  — MERRIMAC    RIVER    AT    MITCHELL'S    FALLS. 
Lone  Tree  hill,    Methuen,   in   the  distance. 


Fig.    174. —  SHIP    ROCK,    PEABODY. 
An  erratic    boulder  of  hornblende  granite. 


POST-PLEISTOCENE  SAND  AND    GRAVEL  327 

and  was  pushed  forward  by  the  glacial  ice,  or  rafted  across  the  valley 
attached  to  the  base  of  a  large  berg,  and  becoming  stranded,  was  left 
where  it  rests  to-day. 

There  are  many  smaller  perched  boulders  on  this  granite  area  (see 
Fig.  175)  and  also  examples  of  boulders  of  erosion  in  situ,  in  all  forms,  from 
large  granite  blocks  where  the  erosion  has  attacked  the  joint-plains  of 
the  massive  ledges  (see  Figs.  176,  177)  to  blocks  that  have  been  eroded 
on  all  sides  and  are  now  simply  boulders.  The  absence  of  soil,  sand,  and 
gravel,  from  about  many  of  these  ridges  of  boulders,  gives  a  free  access 
to  the  air  under  and  around  each  block,  and  thus  preserves  it  from  decay. 
The  drift  on  this  area  is  very  scant,  and  is  usually  boulder-till  covered 
with  disintegrated  granite  rock.  In  some  places  the  disintegrated  granite 
deposit  is  ten  feet  in  thickness  over  the  boulder-till  covering  the  bed- 
rock. In  areas  where  granite  ledges  are  exposed  to  view,  the  northwestern 
side  of  the  outcrop  usually  is  ground  down  to  a  rounded  surface,  even 
when  the  face  of  the  ledge  is  nearly  vertical.     (See  Figs.  176,  177.) 

Disintegrated  granite  is,  without  doubt,  the  result  of  glacial  action. 
In  North  Beverly,  on  Dodge  street,  granite  is  decomposed  to  a  depth 
varying  from  eight  to  twenty  feet.  The  iron  in  the  hornblende  and  free 
magnetite  is  leached  out,  the  feldspars  are  kaolinized,  and  this  liberates 
the  quartz  grains  and  thus  the  granite  is  disintegrated.  This  is  the  re- 
sult of  water-action,  and  as  the  disintegration  of  these  granites  is  always 
on  high  lands,  it  is  fair  to  presume  that  the  water-action  which  leached 
out  the  iron-bearing  minerals  was  the  result  of  the  melting  of  ice  cover- 
ing this  region  during  the  Glacial  period . 

A  series  of  ice-block  holes  occur  at  Lynn  —  Cedar,  Sluce,  Flax,  and 
Glenmere  ponds  —  and  immediately  at  the  north  are  Brown's  and  Spring 
ponds  in  the  town  of  Peabody.  Small  outwash  sand-plains  occur  south 
and  southeast  from  all  these  ponds  in  the  form  of  over  and  outwash 
deposits.  A  subsidence  of  the  land  surface  formerly  covered  this  area 
with  a  sea  of  comparatively  shallow  depth,  and  its  waters  stripped  the 
hillsides  of  their  debris  of  soil,  sand,  and  gravel,  and  left  the  outcropping 
ledges  bare  save  for  the  boulders  stranded  upon  their  summits,  while  the 
valleys  and  sides  of  the  hills  were  covered  with  boulders  rounded  by  gla- 
ciation.  Breed's  and  Holder's  ponds  in  West  Lynn,  are  rock  basins, 
and  the  head-waters  of  small  drainage  streams  which,  flowing  towards  the 
south  between  Walnut  and  Blakely  streets.  West  Lynn,  have  cut  their 
channels  through  the  thin  coating  of  sand,  and  now  flow  over  the  fossili- 
ferous  beds  of  glacial  marine  clay. 


328  POST-PLEISTOCENE   SAND  AND  GRAVEL 

Lake  Quannapowitt,  in  Wakefield,  is  the  site  of  a  large  mass  of  glacial 
ice,  and  is  surrounded  by  overwash  gravels,  alluvial  cones,  terraces,  kames, 
and  sand-plains.  The  ice-contact  on  the  southeastern  shore  of  the  lake 
is  very  marked,  and  extends  southeasterly  across  the  town.  The  mate- 
rial is  coarse  gravel  capped  by  fine  sand.  This  sand,  together  with  other 
deposits,  followed  the  ancient  glacial  drainage-stream,  now  the  Saugus 
river,  in  its  south-southeasterly  course,  and  supplied  the  sands  and  fine 
gravels  which  now  cover  Saugus  and  extend  to  the  sea.  The  streams 
flowing  through  the  valleys  between  the  ancient  volcanic  rocks  and  over 
the  remnants  of  the  Cambrian  sediments  ia  North  Saugus,  carried  these 
sediments  and  blocks  of  Cambrian  conglomerates  across  Lynn  harbor, 
and  in  time  deposited  a  considerable  amount  upon  Nahant.  Erratic 
boulders  of  quartzite  conglomerate  and  volcanic  breccia  from  Castle  hill 
and  Breakheart  hill,  in  Saugus,  are  often  found  on  the  Lynn  harbor  side 
of  Nahant. 

The  area  about  Saugus  and  Lynn  is  deeply  glaciated.  Grooves  and 
scratches  are  to  be  seen  on  the  surfaces  of  all  outcropping  ledges,  and  always 
run  in  a  northwesterly  to  southeasterly  direction.  Boulder-till  is  found 
in  varying  depths  in  all  parts  of  the  region  where  excavations  have  been 
made  for  gravel.  This  boulder-till  forms  a  covering  over  the  bed-rock, 
and  is  usually  composed  of  local  materials  —  quartz  diorite  granite,  and 
angular  fragments  of  the  ancient  volcanic  rocks,  mixed  with  sand,  gravel, 
and  clay  —  a  typical  boulder-till  with  no  form  of  stratification. 

Cape  Ann,  from  Beverly  to  Rockport,  is  an  area  of  intense  glaciation 
and  post-glacial  erosion.  The  surfaces  of  all  outcropping  ledges  of  horn- 
blende granite  and  syenite  have  been  rounded  and  smoothed  on  the  sides 
and  summits  and  then  stripped  of  debris  by  sea-action.  (See  Fig.  178.) 
Niles'  pond  on  Eastern  point,  westerly  from  Brace's  cove,  is  a  shallow, 
glacial  basin,  having  a  barrier  just  above  sea-level  in  Brace's  cove,  over 
which  extremely  high  seas  often  break.  (See  Fig.  179.)  This  pond  at 
some  earlier  time  probably  was  a  lagoon,  back  of  the  barrier  which  might 
be  called  a  tombola.  Several  good  examples  of  augite  syenite  (akerite) 
glacial  erratic  boulders  are  found  perched  upon  hornblende  granite  out- 
cropping ledges  in  the  area  known  as  Beverly  common  pastures,  on  the 
southeastern  part  of  Bald  hill.  The  syenite  appears  by  the  side  of  the 
road,  and  at  the  northeast,  about  one  mile  and  a  half  distant,  a  large 
boulder  of  syenite,  known  as  "bung-stopper  rock,"  is  perched  upon  a 
granite  ledge.  Several  large  square  boulders  of  granite  are  found  on  the 
augite  syenite  area  of  Bald  hill.     Probably  they  are  erratics  from  Wen- 


Fig.    175.  — HORNBLENDE    GRANITE    BOULDER. 
Perched   upon  boulders  eroded  in    situ,    Peabody. 


U'-:, 


£S4<  r'^v. 


...    M 


j^y 


Fig.    176    —  HORNBLENDE    GRANITE    BOULDERS    ERODED    IN   SITU. 
Peabody. 


Fig.    177.— HORNBLENDE   GRANITE    LEDGE    AT    PEABODY,     SHOWING    HORIZONTAL   JOINTING. 


Fig.   178.  — SYENITE    LEDGE    ROUNDED    BY    THE    ACTION    OF   GLACIAL    ICE. 
East  Gloucester. 


Fig.    179.  — NILES'    POND,    EASTERN    POINT. 
Gloucester. 


Fig.    180.  — HARD-PACKED    BOULDERY    GRAVEL    COVERED    BY    A    IVIORAINE    OF    BOULDERS. 
Gloucester. 


POST-PLEISTOCENE   SAND  AND   GRAVEL  335 

ham  or  Hamilton.  Under  these  boulders,  where  the  surface  of  the  ledge 
has  been  protected  from  the  weather,  it  is  usually  glaciated  by  scratches 
and  fine  striations. 

Squam  river,  in  Pre-Glacial  times,  was  a  small  stream  draining  the 
region  of  Gloucester,  West  Gloucester,  and  Rockport.  During  the  Gla- 
cial period  its  channel  was  broadened  and  cut  down  to  a  considerable 
depth  by  the  advancing  ice,  which  also  formed  Gloucester  harbor.  The 
deep  channel  that  was  formed,  in  Squam  inlet  has  since  been  filled  with 
detrital  material  brought  in  by  the  sea.  In  1643  ^  cut  or  canal  was  dug, 
connecting  Gloucester  harbor  with  Squam  inlet,  and  thereby  Rockport 
and  a  part  of  Gloucester  became  an  island  at  high  tide.  From  the  appear- 
ance of  the  shore  on  either  side  of  the  cut,  the  early  excavations  above 
the  sea  beach  were  made  through  boulder-till,  deposited  there  under  the 
glacial  ice.  Severe  storms  have  at  times  filled  this  cut  with  sand  and 
gravel.  In  1829  it  was  deepened  and  enlarged  by  the  Gloucester  Canal 
Company,  and  since  then  the  tide  has  ebbed  and  flowed  through  the  canal 
without  interruption.  The  drainage  area  occupied  by  the  inlet  was 
formed  at  a  contact  of  the  hornblende  granite  and  a  massive  syenite 
rock  —  nordmarkite.  Probably  much  iron  was  at  that  time  formed,  and 
upon  oxidation  was  easily  removed  by  stream-action,  thus  defining  the 
bed  of  the  ancient  drainage  stream.  Nordmarkite  has  been  previously 
mentioned  as  granophyric  granite.     It  is  a  form  of  augite  syenite. 

During  Inter-Glacial  times  the  entire  coast-line  of  Essex  County,  with- 
out doubt,  was  quite  different  in  outline  from  that  of  to-day.  The  islands 
which  fringe  the  mainland  were  formerly  its  outer  edge.  The  inner  har- 
bor at  Gloucester  was  then  dry  land,  and  Eastern  point  was  connected 
with  "Norman's  Woe,"  a  small  stream  flowing  into  the  outer  harbor 
from  Squam  river,  alone  separating  the  points.  Towards  the  northeast. 
Eastern  point  was  connected  with  Salt,  Milk,  and  Thatcher's  islands,  and 
Londoner  rock  off  Rockport.  The  bed-rock  of  the  mainland  and  of  the 
skirting  islands  is  of  the  same  formation.  From  a  study  of  the  action  of 
the  sea  in  cutting  back  the  cliffs  arid  headlands,  it  is  safe  to  assume  that 
the  waves,  aided  by  an  advancing  glacier,  might  have  scoured  out  the 
present  harbors  and  removed  all  the  land  forms  within  several  miles  of 
the  coast-line  in  the  space  of  a  very  few  thousand  years. 

The  present  drainage  system  of  this  area  seems  to  be  the  same  as  in 
Pre-Glacial  times.  The  streams  flow  northerly  and  northeasterly  in  the 
valleys  occupied  by  them  before  the  Glacial  period.  The  glacial  drainage 
and  the  glacier  itself  flowed  in  the  opposite  direction.     In  a  few  instances 


336  POST-PLEISTOCENE  SAND  AND   GRAVEL 

where  soft  rocks  occurred,  the  glacial  streams  were  enabled  to  cut  down 
their  beds  and  capture  the  stream,  and  thus  have  been  preserved  to  the 
present  time.  The  Saugus  river,  from  Wakefield  to  the  sea,  is  an  example, 
and  the  various  inlets  or  drowned  stream-valleys  flowing  into  Salem  harbor 
from  Danvers  are  other  excellent  examples. 

Nearly  the  entire  surface  covering  the  bed-rock  of  Gloucester  and 
Rockport  is  boulder-till  capped  with  hard-packed  bouldery  gravel  in 
varying  thickness.  (See  Fig.  i8o.)  The  latter  was  probably  deposited 
from  material  incorporated  in  the  base  of  the  glacial  ice,  which,  upon 
melting,  left  these  bouldery  gravels.  This  gravel  may  be  seen  in  road- 
side cuttings  and  in  gravel-pits.  The  materials  from  which  it  is  com- 
posed are  heterogeneously  mixed  together  without  the  slightest  indica- 
tion of  stratification.  Thus,  in  form,  it  is  like  boulder-till,  yet  imlike  it, 
for  little  or  no  clay  is  mixed  with  the  boulders  and  gravel.  Dogtown 
Common,  at  Gloucester,  was  in  front  or  at  the  east  of  the  boulder-belt. 
It  is  covered  by  a  low,  rolling  ridge,  apparently  a  kame-plain  of  sandy 
gravel.  Upon  this  area  many  of  the  early  settlers  built  their  houses, 
and  numerous  cellar-holes,  fenced  fields  and  pastures  are  yet  to  be  seen. 
(See  Figs.  i8i,  182.)  This  kame-plain  indicates  that  subglacial  stream 
drainage  deposited  the  sand  and  gravel  on  the  surface  of  the  boulder- 
till.  The  serpent  kame  or  osar,  near  the  Rockport  railroad  station,  is 
also  a  deposit  of  sand  and  gravel  marking  the  course  of  a  subglacial 
stream  that  flowed  under  the  glacial  ice-cap  on  the  surface  of  boulder- 
till.  Pigeon  hill,  southwest  of  Pigeon  Cove  harbor,  is  a  typical  drum- 
lin  of  boulder-till.  In  this  till  are  found  boulders  and  pebbles  of  the 
hornblende  granite  of  the  region ;  granite  gneiss  from  Boxford  and  Ando- 
over ;  porphyritic  granite  from  Amesbury ;  a  coarse  feldspar  granite,  prob- 
ably from  Jackmantown,  Maine ;  and  felsite  and  diorite  from  Rowley. 

A  moraine  of  boulders  near  the  Beach  Grove  cemetery  at  Rockport 
forms  for  nearly  three  hundred  yards  an  irregular  wall  some  fifty  feet  in 
width.  (See  Figs.  183,  184.)  These  boulders  are  nearly  all  of  large  size, 
some  of  them  weighing  one  or  two  tons  each.  They  are  in  rounded  to 
subangular  form,  and  become  a  striking  feature  in  the  landscape  as  they 
are  deposited  upon  high  ground.  This  moraine  marks  a  halting-place  of 
the  great  continental  ice-sheet  in  its  retreat  northward  at  the  close  of  the 
Glacial  period.  It  follows  the  slope  of  the  hill,  and  at  a  point  about 
two  hundred  yards  southeast  of  Beach  Grove  cemetery,  it  occupies  a 
drainage-crease  in  the  bottom  of  a  steep-sided  valley,  where  the  boulders 
are  piled  in  great  profusion  and  crop  out  from  beneath  the  present  surface. 


Fig.    181.— MORAINES    OF    BOULDERS    AT    ROCKPORT. 
Showing  a  lialting  place  of  the  glacial   ice,   northeast  of  Dogtown  common,   during  its  retreat   fr( 


-GLACIAL    ERRATIC    BOULDERS    AT    DOGTOWN    COMMON. 

Sloucester.     The  walled   areas  formerly  were  cultivated. 


-1#il^>*f: 


Fig  183.  — MORAINES    OF    BOULDERS,    EAST    OF    BEACH    GROVE    CEMETERY,    ROCKPORT. 


If   JKS^^mSk  '■' 

-.            J 

>jH 

% 

^  ^"y 

:>■< 

1 

H|K^l_v3J3S 

MMi 

^^^^^^^ 

im 

Fig.    184.— ANOTHER    VIEW    OF    THE    ABOVE. 


Fig.    185.  — WOLF    HILL,    GLOUCESTER. 
Perched  glacial  boulders  upon  Its  summit. 


Fig.    186.  — DRAINAGE    CREASE    AT    MANCHESTER. 
The  outlet   from  a  large  valley  at  the  west  which   was  filled  with  gla 


POST-PLEISTOCENE   SAND  AND   GRAVEL  343 

From  the  valley  the  moraine  extends  to  the  swamp  at  the  northern  end 
of  Cape  pond,  where  it  expands,  and  the  boulders  are  scattered  in  an  irregu- 
lar line  reaching  to  the  sea-shore  near  East  Gloucester. 

Glacial  erratic  boulders  and  blocks  of  granite  are  scattered  over  the 
whole  surface  of  Essex  County,  but  at  Gloucester  and  Rockport  such 
boulders  are  found  on  the  summits  of  the  high  lands,  and  also  are  perched 
upon  many  of  the  granite  ledges,  which  still  retain  glacial  grooves  and 
scratches  under  the  protecting  boulders.  (See  Fig.  185.)  These  glacial 
scratches  and  striae  have  a  northwesterly  to  southeasterly  direction,  some- 
times with  a  slight  variation  to  the  east,  and  indicate  that  these  erratic 
boulders  and  blocks  of  granite,  especially  those  on  the  high  land  of  Dog- 
town  Common,  have  been  transported  here  from  higher  elevations  towards 
the  northwest,  probably  from  Annisquam  or  West  Gloucester. 

At  Manchester,  north  of  Summer  street,  the  entire  area  extending 
to  Long  hill  is  covered  by  a  series  of  short  terraces  and  sand-plain  de- 
posits. In  the  Essex  and  Manchester  woods,  the  great  swamp  that  ex- 
tends from  Millstone  hill  shows  on  its  southeasterly  shore  a  series  of 
terraces  that  were  formed  when  the  swamp  was  a  lake  of  considerable 
extent.  Tliese  terraces  are  the  result  of  changes  of  water-level  in  the 
lake,  as  the  shore  does  not  indicate  an  ice-contact,  and  no  outwash  or 
overwash  gravels  are  to  be  found  in  front  of  the  terraces;  in  fact,  the 
whole  surface  of  the  area  towards  the  east  and  southeast  is  washed  clean 
of  debris  except  in  a  few  deep  pockets  between  the  outcropping  ledges. 
On  the  Essex  river,  between  Chebacco  lake  and  the  village  of  Essex,  there 
are  terraces  and  stream-cuttings  through  the  clay,  sand,  and  gravel.  In 
the  boulder-till,  at  the  base  of  Perkins'  and  White's  hills,  steep  terraces 
of  sand  and  gravel  are  to  be  seen  in  the  valley  through  which  the  railroad 
passes.  Probably  stream-cutting  has  produced  the  numerous  terraces 
which  extend  to  the  tidal  marsh.  Terraces,  sand-plains,  and  moraines 
of  boulders  cover  the  surface  of  South  Essex  and  West  Gloucester,  and 
extend  to  Long  hill  and  the  magnolia  swamp  at  the  base  of  Mount  Ann. 
This  swamp,  which  reaches  for  over  a  mile  towards  the  southwest,  was 
formerly  an  ice-block  hole,  but  is  now  entirely  filled  with  peat  and  cov- 
ered by  forest  growth.  Outwash  gravels  and  their  deposits  of  sand 
also  fill  the  valleys  between  Mussel  point  and  Kettle  cove  at  Manchester. 
East  of  the  railroad  station  at  Magnolia  is  a  remarkable  moraine  of  boulders 
occupying  a  drainage-crease  or  valley  by  the  roadside,  and  having  in 
front  an  outwash  sand-plain.     (See  Fig.  186.) 

Ice-block  holes  occur  in  Rockport  although  Cape  pond  was  probably 


344  DRUMLINS    CARVED    BY    LANDSLIDES 

formed  by  moving  ice.  At  the  southern  and  southeastern  end  of  the  pond, 
the  drift  is  seen  in  short  ridges  of  gravel  in  the  valleys  between  the  granite 
out-crops  (see  Fig.  187),  and  northeasterly  from  the  pond  there  is  a  peat 
swamp  which  was  undoubtedly  the  site  of  an  ice-block.  Northwesterly 
from  the  pond  there  is  another  peat  swamp,  which  was  an  ice-block  hole, 
having  a  contact  towards  the  south  with  gravels  extending  around  Railcut 
hill  to  Long  beach. 

The  most  striking  feature  of  the  glaciation  of  Gloucester  and  Rock- 
port  is  the  boulders  which  cover  the  surface.  Many  of  these  are  boulders 
of  erosion  in  situ,  which  are  continually  creeping  down  the  steep  hillsides 
to  accumulate  in  the  valleys.  There  are  also  moraines  of  boulders  piled 
in  windrows,  large  erratic  blocks  resting  upon  boulder-till,  and  boulders 
perched  upon  the  glaciated  surfaces  of  outcropping  granite  ledges. 

The  Raccoon  rocks  in  the  Essex  and  Manchester  woods  is  an  out- 
cropping granite  ledge,  whose  northwestern  face  has  been  broken  down 
by  the  action  of  the  frost.  (See  Fig.  77.)  The  entire  face  of  the  ledge, 
from  the  great  swamp  to  Wyman's  hill  in  Manchester,  is  a  crumbling 
mass  of  angular  fragments.  Large  masses  of  the  rock  are  forced  out- 
ward nearly  every  winter  by  the  action  of  water  freezing  in  the  cracks 
and  crevices,  the  debris  falling  into  the  swamp  below.  In  1887,  a  large 
cave  existed  in  this  ledge,  the  mouth  of  which,  a  few  years  later,  was 
covered  by  a  large  fragment  of  rock  weighing  several  tons,  which  had 
fallen  from  the  face  of  the  ledge  above. 

Moses'  mountain,  Manchester,  is  a  massive  outcrop  of  hornblende 
granite,  the  entire  surface  of  which  is  well  rounded  and  smoothed  by 
glacial  ice.  Sunset  rock,  or  the  Agassiz  boulder,  is  a  large  mass  of 
granite  perched  upon  a  granite  ledge  beside  the  road  leading  from  Man- 
chester to  Essex ;  and  in  the  swamp  north  of  this  boulder  there  is  a  series 
of  large,  erratic  boulders,  one  of  which  is  the  largest  boulder  in  Essex 
County.  It  is  a  rounded  mass  of  syenite  akerite,  thirty-two  feet  in  height 
above  the  surface  of  the  swamp.  It  is  thirty-five  feet  wide  and  forty 
feet  long,  and  is  estimated  to  contain  44,800  cubic  feet  of  granite  weigh- 
ing 3,763  tons.  A  white  pine  tree,  Pinus  strobus,  is  growing  on  the  top 
of  this  boulder,  its  roots  extending  into  a  crack  or  joint-plain.  (See 
Fig.  80.) 

Drumlins  Carved  by  Landslides.  —  During  the  spring  months,  the 
surfaces  of  drumlins  whose  slopes  are  steep,  become  saturated  with  water 
from  melting  snow  and  rain,  and  certain  areas  of  the  upper-till  frequently 
slip  down  on  a  more  clayey  and  compact  part  of  the  till  beneath,  result- 


Fig.   187.  — CAPE   POND,    ROCKPORT. 


Fig.   188.  — INCIPIENT    LANDSLIDE    ON   BRAKE    HILL,    WEST    NEWBURY. 


Fig.    189.  — MATURE    LANDSLIDE    ON    LONG    HILL,   WEST    NEWBURY. 


Fig.    190. —ANOTHER    VIEW    OF   THE    ABOVE. 


Fig.    191  .  —  ADOLESCENT    LANDSLIDE,    HOG    ISLAND,    ESSEX. 

The  slide  has  formed  a  bench  neat  the  fifty-foot  contour  line  fronn  which  spring-water  continually 

flows  down  the  hill. 


Fig.    192.  — NORTH    RIDGE,   JEFFREY'S    NECK,    IPSWICH,    AS    SEEN    FROM    EAGLE    ISLAND. 
Showing  a  live   landslide  around  the  base  of  the  ridge  and  above,   a  grass-grown   bench  of  an  earlier  slide 


DRUMLINS   CARVED    BY    LANDSLIDES  351 

ing  in  an  incipient  landslide  or  washout.  (See  Fig.  i88.)  As  the  wash- 
out becomes  more  powerful,  the  scarp  creeps  up  the  hill,  and  widens, 
and  each  season  water  continues  to  issue  from  the  starting-point  on  the 
hillside.  This  point  is  indicated  in  the  illustration  by  the  man  stand- 
ing. This  flow  of  water  continues  to  undermine  the  till,  and  large  masses 
are  washed  down,  to  form  a  delta  at  the  base  of  the  hill.  An  excellent 
example  of  a  mature  landslide  may  be  seen  on  the  northern  side  of  Long 
hill  in  West  Newbury.  (See  Figs.  189,  190.)  Here  the  whole  slope  of  the 
hill  is  gradually  sliding  down  and  forming  a  false  scarp  which  is  over 
five  hundred  yards  long  and  forty  feet  in  its  maximum  height.  During 
the  spring,  and  also  in  other  wet  seasons,  water  in  considerable  volume 
issues  from  fifteen  or  more  places  on  the  face  of  this  scarp,  and  under- 
mines large  masses  of  the  till,  which  gradually  slide  down  the  surface 
of  the  slope,  removing  at  the  same  time  growths  of  trees,  bushes, 
and  grass,  some  of  which  afterwards  take  root  where  they  are  finally 
deposited.  In  Figs.  189  and  190,  large  trees  of  pine,  elm,  cherry,  and 
apple  are  to  be  seen  growing  at  the  base  of  the  scarp.  The  gravel,  sand, 
and  clay  resulting  from  this  landslide  spread  out  and  form  a  delta  on 
the  fields  at  the  base  of  the  hill,  while  much  of  the  clayey  sediment 
washes  down  the  stream  formed  below  the  hill,  and  flows  into  the  Merri- 
mac  river. 

Examples  of  landslides  on  the  surfaces  of  drumlins  are  to  be  found 
in  many  parts  of  the  County,  some  of  which  exhibit  a  complete  cycle 
from  the  incipient  stage  to  the  adolescent  and  mature.  The  latter  is  to 
be  seen  when  the  gradient  on  the  face  of  the  hill  has  so  far  leveled  its 
slope  that  grass  and  bushes  cover  the  surface  and  all  that  remains  to 
record  the  landslide  is  the  bouldery  grass-grown  scarp  with  a  sluggish 
spring  issuing  from  the  base  of  the  hill.     (See  Fig.  191.) 

North  ridge,  a  massive  drumlin  forming  the  northern  part  of  Great 
Neck,  Ipswich,  has  two  landslides  on  its  northwestern  slope  opposite 
Eagle  hill.  (See  Fig.  192.)  The  northern  slope  of  this  hill  exhibits  a 
series  of  landslides  in  various  stages  of  development,  from  the  inci- 
pient to  the  adolescent  and  mature.  On  one  part  of  the  hill  a  number  of 
benches  have  been  formed,  all  of  which  are  more  or  less  grass-grown. 
Near  the  siunmit  of  the  highest  bench  is  a  perpendicular  scarp  from  two 
to  ten  feet  high,  the  base  of  which  slips  down  a  little  each  season,  and 
undoubtedly  in  time  will  slip  into  Plum  island  sound.  Another  example 
of  an  adolescent  landslide  may  be  seen  on  the  northeastern  slope  of  Stage 
hill,  opposite  Little  Neck,  Ipswich.     A  deep  gulch  or  crease  filled  with 


352  DRUMLINS    CARVED    BY    LANDSLIDES 

boulders  and  a  series  of  springs  at  the  base  of  the  hill,  together  with  a  grass 
grown  scarp  reaching  to  the  top,  indicate  where  the  landslide  occurred. 

Brown's  hill,  Hamilton,  a  round  hill  of  very  compact  boulder-till, 
also  shows  an  adolescent  landslide  where  the  graded  grass-grown  scarp 
slopes  down  to  a  ravine  on  the  northwestern  part  of  the  hill,  in  which 
are  a  number  of  steep-sided  water-holes,  and  below  them  a  swampy 
area.  Sagamore  hill,  Essex,  a  long,  rambling  drumlin,  shows  unmistak- 
able evidence  that  a  landslide  has  carved  its  surface.  Graded  slopes 
reach  downward  from  the  summit  of  the  hill  nearly  to  its  base,  where  a 
number  of  springs  and  water-holes  break  out  in  the  springtime  and  also 
in  very  wet  seasons.  If  the  slope  from  the  valley  were  more  abrupt,  the 
steep-sided  water-holes  thus  formed  would  cause  a  new  landslide. 

Ox  pasture  hill,  Rowley,  presents  an  excellent  example  of  an  ado- 
lescent landslide.  On  its  western  slope,  at  an  elevation  of  one  hun- 
dred feet,  is  a  well-defined  bench,  and  a  number  of  feet  higher  there 
is  another.  These  benches  were  caused  by  landslides,  in  which  large 
masses  of  the  surface  of  the  hill  have  slid  downward  towards  its  base. 
Both  benches  are  well-defined,  as  are  the  grass-grown  scarps.  A  ravine, 
well  up  the  hillside,  in  which  the  stream  still  flows  from  the  face  of  the 
scarp,  is  covered  with  forest  trees.  Hunslow  hill  at  Chaplinville,  in  Row- 
ley, has  evidence  of  an  adolescent  landslide  on  the  northeastern  part 
of  the  hill  at  an  elevation  of  two  hundred  and  fifty  feet.  The  face  of 
the  hill  has  been  cut  down  from  near  the  summit,  leaving  a  grass-grown 
scarp  nearly  one  thousand  yards  in  length  with  a  maximum  height  of 
one  hundred  and  fifty  feet.  A  bench  has  been  formed  that  is  now  cov- 
ered with  a  growth  of  bushes  and  forest  trees.  Another  example  of  a 
landslide  may  be  seen  on  the  northern  side  of  Kimball's  hill.  East  Ha- 
verhill, where  the  scarp  has  formed  a  half-circle  or  ox-bow,  as  the  water 
flowing  from  the  base  of  the  hill  has  undermined  the  till  and  cut  a  chan- 
nel through  a  small  valley  in  the  old  scarp.  Crowninshield's  hill,  a  drum- 
lin in  the  southern  part  of  Topsfield,  shows  a  steep,  adolescent  landslide, 
the  sand  and  gravel  from  the  wash  of  the  slide  forming  a  large  sand- 
plain  and  ridge  towards  the  southeast  in  Blindhole  swamp.  The  land- 
slide divides  the  hill  into  two  parts,  over  which  the  Newburyport  and 
Boston  turnpike  crosses  where  the  ravine  runs  nearly  east  and  west. 
Beyond  the  road,  towards  the  west,  the  scarp  and  ravine  wind  south- 
westerly. The  water-hole  where  the  landslide  first  started  may  yet 
be  seen  in  the  eastern  side  of  the  hill,  and  following  up  the  ravine  a  series 
of  these  water-holes  also  occur  at  intervals. 


Fig.    193.  — PLAN   OF  THE   VALLEY  OF    PORTER'S    RIVER,    EAST   DANVERS. 

•  Old  Clay-pits. 

•  I    Leda-clay.      Edward  Carr  clay-pit. 

•  2  Leda-clay.     Peabody   Pottery   clay-pit. 
T.    Boulder-till. 


-CLAY-BEDS    COVERED    BY    A   THIN    COATING    OF    RIVER    SILT    AND    SAND. 
West  side  of  the  Merrimac  river  near   Mitchell's  falls,    Haverhill. 


Fig.    195.  — DANVERSPORT,    SHOWING    THE    AREA    COVERED    BY    BRICK-CLAYS. 
Folly  hill   in  the  distance. 


CHAPTER  XI 

CLAYS 

In  Essex  County  was  the  beginning  of  brickmaking  and  the  earthen- 
ware industries  of  New  England.  Over  two  hundred  years  ago  it  was 
famous  for  its  manufactures  from  clay.  Clay-beds  have  been  worked 
for  brickmaking  in  nearly  every  town  and  village  in  the  County,  and 
Newburyport,  Beverly,  Peabody,  and  Danvers  still  continue  the  pro- 
duction of  earthen-waj-e.  At  the  present  time  bricks  are  made  in  twelve 
different  cities  and  towns  in  the  County. 

Residual  Clays,  formed  from  the  decomposition  of  ledge  rock  in  situ 
are  rare  in  Essex  County.  One  bed,  which  was  probably  decomposed  from 
a  ledge  of  felsite,  occurs  on  the  west  side  of  Kent's  island,  Newbury,  and 
is  now  a  very  fine  white  kaolin.  The  deposit  has  not  been  worked  and 
its  extent  is  unknown.  A  mug  made  from  this  clay  at  the  Beverly  Pottery 
burned  out  white.  Another  mass  of  residual  clay  occurs  in  South  Law- 
rence, and  is  the  result  of  the  decomposition  of  a  ledge  of  gneissic  granite, 
quartz  being  absent. 

Upper  Clays,  used  for  bricks  and  pottery,  were  without  doubt  laid 
down  in  fresh  water,  for  it  is  well-known  among  workers  in  pottery  clay 
that  the  flooding  of  sea-water  upon  the  surface  of  a  clay-pit  renders  the 
deposit  unfit  for  use.  Such  clay  when  baked  in  the  kiln  will  not  retain 
a  glaze  for  it  will  slip  from  the  surface.  These  upper  clays  are  of  vary- 
ing thickness  in  different  beds.  In  a  brick-clay  pit  at  Danversport,  owned 
by  Edwin  Day,  the  clay  is  eighteen  feet  deep  below  the  tidal-marsh  on 
the  banks  of  Waters'  river.  Without  doubt  this  is  an  upper  clay,  for 
no  fossils  have  been  found,  or  evidences  of  any  kind  that  might  connect 
it  with  the  marine  or  leda-clays.  The  upper  clays  on  the  bank  of  Crane 
river  in  Danvers,  are  twelve  or  more  feet  in  thickness.  They  are  cov- 
ered by  a  bank  of  sandy  gravel  some  fifteen  feet  in  depth,  and  rest 
upon  a  parting  of  water- worn  gravels  six  inches  in  thickness,  beneath 
which  the  blue  to  black  leda-clays  are  deposited  which  are  below  the 
level  of  the  sea.  The  brick-clay  in  Edward  Carr's  pit  near  Liberty 
street,  Danvers,  is  capped  with  about  one  foot  of  soil  and  sandy   gravel, 

357 


358  MANUFACTURES    OF    CLAY 

beneath  which  the  clay  is  found  to  vary  from  eight  to  twelve  feet  in. 
thickness,  and  is  interrupted  every  few  inches  by  a  parting  of  fine  sand. 
(See  Fig.  193.) 

At  Haverhill,  the  brick-clays  usually  rise  to  the  surface  and  are  of 
unknown  depth.  (See  Fig.  194.)  One  pit  near  the  Haverhill  and  Grove- 
land  bridge  has  been  excavated  to  a  depth  of  thirty  feet  below  the  sur- 
face. The  clay  is  of  a  reddish-gray  color,  and  is  composed  of  fine  mud 
with  no  gravel  or  sand  partings.  Boulders  and  pebbles  are  rarely  found. 
It  is  easily  worked  and  may  be  drawn  upon  a  potter's  wheel  into  very 
long,  thin  ware,  and  takes  a  fine  glaze.  The  clay  found  at  Newbtiry- 
port  is  of  the  same  reddish-gray  color  as  the  last,  but  it  contains  numer- 
ous partings  of  sand,  some  of  which  are  six  feet  in  depth.  A  well  driven 
to  the  depth  of  one  hundred  and  eighty  feet  did  not  pass  through  the 
deposits.  The  brick-clays  at  Ipswich  are  found  in  low-lying  tracts  of 
land  not  more  than  six  feet  above  the  surface  of  the  meadow.  The  clay- 
beds  are  from  eight  to  ten  feet  below  the  surface,  and  at  the  present  time 
are  so  much  below  the  drainage  level  of  the  area  that  they  are  not  worked. 
The  clays  found  at  Beverly  are  all  below  mean  sea-level,  but  are  of 
superior  quality  for  making  pottery.  Salem  clay  deposits,  a  munber  of 
years  ago,  were  excavated  to  a  point  below  the  drainage  level  of  the 
region,  and  the  industry  of  brick-  and  pottery-making  therefore  ceased  to 
be  profitable. 

Four  ounces  of  clay  from  the  brick-clay  pit  of  Edward  Carr,  Liberty 
street,  Danvers,  when  washed,  gave  one  ounce  of  fine  sand,  the  residue 
being  silty  mud,  which  in  ten  hours'  time  settled  to  the  bottom  of  a  jar 
of  water,  leaving  the  water  clear.  The  color  of  this  clay  is  reddish-gray, 
and  a  sample  taken  seven  feet  below  the  surface,  under  microscopical 
examination,  was  found  to  be  composed  of  grains  of  feldspar,  quartz, 
mica-plates,  epidote,  chlorite,  and  a  fiocculent  mass  of  chlorite  and  kaolin. 

Manufactures  of  Clay.  —  Common  bricks,  to  the  number  of  13,535,000, 
are  made  annually  in  Essex  County.  Danvers  and  Lynn  produce  4,000,000 
pressed-bricks,  and  1,800,000  feet  of  fire-proofing  is  made  from  clay  by  the 
New  England  Fire  proof  Manufacturing  Company  of  Newburyport.  The 
Beverly  Pottery  (Estate  of  Charles  A.  Lawrence)  manufactures  183,500 
pieces  of  earthen-ware  annually,  and  the  Peabody  Pottery  Company  (Moses 
B.  Paige)  produces  about  the  same  number.  These  two  potteries  use 
about  six  hundred  tons  of  clay  each  year.  The  Nickerson  Pottery  Com- 
pany of  Newburyport  manufactures  fine  ware  from  residual  clays  brought 
from  Ohio,  mixed  with  Newburyport  clay,  hematite,  etc.     The  Danvers 


Fig.    196.  — LEDA-CLAY    IN    BOTTOM    OF    EDWARD    CARR    CLAY-PIT. 
Liberty  street,    Danversport.      Location  of  fossils  is   indicated   by  dots. 


Fig,    197.  — PEABODY    POTTERY   COMPANY'S   CLAY-PIT    NEAR    PURCHASE    STREET, 
Danvers.      Location  of  Portlandia  Arctica  fossils  is  indicated   by  dots. 


^Sia. 


c 


A 


Fig.    198.  — CROSS-SECTION    OF  THE   VALLEY   OF    CRANE    RIVER,    DANVERS. 

I  .    Peabody  Pottery  Company's  clay-pit.  2.    Crane  river. 

A.    Leda-clay.      B.    Sandy  gravel.     C.    Brick-clai(.     T.    Boulder-till.      D.    Sand  and  soil. 


i^*?5S^?jS'j?v-^.i5^!m5>y}(^Ji^?/^^ 


Fig.  199.-  CROSS-SECTION    OF  THE    CLAY-PIT  OF   THE    PEABODY    POTTERY   COMPANY. 

Near   Purchase  street.   Danvers, 

A.    Leda-clay,   showing  position  of  fossils  of  Portlandia  Arctica.     B.    Sandy  gravel. 

C.    Reddish-gray  brick-clay.      D.    Sand   and  soil. 


GLACIAL    MARINE    OR    LEDA-CLAYS  363 

clays  are  also  used  at  the  cast  steel  forge  works  in  Lynn,  five  htindred 
tons  from  the  leda-clay  pit  on  Liberty  street  being  used  annually  (1904). 

Glacial  Marine  or  Leda-Clays.  In  Essex  County  these  clays  are  com- 
posed of  fine  mud,  silt,  and  sand  deposited  by  the  waters  melting  from 
glacial  ice  in  front  of  the  land  ice,  and  probably  situated  in  bays  and 
estuaries  formerly  existing  along  the  coast. 

The  depth  of  these  deposits  with  few  exceptions  is  unknown.  In  the 
clay-pit  on  Liberty  street  in  Danvers,  a  boring  was  made  to  the  depth  of 
forty  feet  without  passing  through  the  clay.  On  Bridge  street  in  Salem, 
the  gas  company  drove  a  well  through  seventy-two  feet  of  clay  before 
reaching  gravel  and  a  good  supply  of  water. 

The  leda-clay,  so  far  as  examined,  contains  fossils  only  locally.  In 
the  Carr  clay-pit,  Danvers,  the  fossils  first  collected  were  found  in  the  ex- 
treme southern  portion  of  the  pit,  the  deposit  extending  into  the  face 
of  the  bank  about  eight  feet.  As  the  clay  was  removed  from  this  bank, 
the  author  collected  many  perfect  shells  and  hundreds  of  fragments.  Not 
long  after,  at  a  point  about  one  hundred  feet  northeasterly  from  the 
first  bed  of  fossils,  another  bed  was  imcovered,  and  for  a  space  of  ten 
feet,  in  a  slight  dip  in  the  clay,  Portlandia  Arctica  occurred.  The  larger 
number  of  fossils  were  collected  in  deeper  holes  opened  in  the  bottom 
of  the  pit,  although  many  of  the  openings  made  were  entirely  barren 
of  results.  The  men  who  are  working  the  clay  rarely  notice  the  fossil 
shells,  or,  if  they  do,  the  fact  is  concealed  from  a  fear  that  the  fossils  may 
injure  the  reputation  of  the  clay  for  brickmaking. 

The  upper  brick-clays  contain  numerous  pebbles  and  small  boulders, 
which  seldom  weigh  more  than  one  himdred  pounds,  and  which  are  usually 
well-rounded  pieces  of  hornblende  granite  or  diorite  —  local  bed-rock 
from  the  region.  Sand  and  gravel  partings  are  found,  indicating  seasons 
of  swiftly  flowing  water  when  the  boulders  might  have  been  transported, 
especially  if  partially  buoyed  up  by  ice.  The  leda  glacial  marine  clays 
contain  only  a  few  small  pebbles,  seldom  weighing  over  two  poimds  each, 
and  with  an  occasional  small  pebble  of  granitic  gneiss. 

Fossil  shells  were  first  discovered  by  the  author  in  April,  1902,  in  a 
clay-pit  opened  by  the  Peabody  Pottery  on  the  bank  of  Crane  river, 
Danvers,  a  small  tidal-stream.  (See  Fig.  197.)  This  river  has  cut  its 
bed  through  a  bank  of  sandy  gravel  some  fifteen  feet  in  thickness.  Under 
the  gravel  is  a  deposit  of  reddish-gray  pottery-  or  brick-clay,  twelve  or 
more  feet  in  thickness,  below  which  is  thin  parting  of  coarse  gravel  about 
eight  inches  deep,  and  below  this  a  blue  to  black  clay  of  unknown  depth. 


364  GLACIAL   MARINE   OR   LEDA-CLAYS 

the  surface  of  which  is  below  mean  sea-level.  This  blue  clay  contains 
thousands  of  fossil  shells,  which  occupy  an  undulating  series  of  lines,  from 
a  few  inches  to  two  feet  wide,  across  the  side  of  the  pit,  and  running  in  a 
northwesterly  to  southeasterly  direction.  The  clay  is  bedded,  and  the 
dip  of  the  beds  is  very  marked,  being  about  25°  southwest.  Upon  split- 
ting the  clay  along  the  bedding  planes,  numerous  fossil  shells  were  ex- 
posed to  view  (see  Figs.  198,  199),  which  proved  to  be  Portlandia  Arc- 
tica.  Gray,  all  being  small  in  size,  none  measuring  over  8  mm.  long  by 
6  mm.  wide.  No  other  species  of  fossil  shells  were  found.  This  was  the 
first  time  that  this  fossil  shell  had  been  foimd  in  the  clays  of  Massachusetts. 
The  most  important  deposit,  as  regards  the  number  of  species  of 
fossils,  was  found  in  Edward  Carr's  clay-pit  on  Liberty  street,  Danvers. 
The  clay  was  from  eight  to  fifteen  feet  in  thickness,  and  was  covered  by 
one  or  two  feet  of  soil  and  sandy  gravel.  (See  Fig.  196.)  Several  hun- 
dred fossil  shells  were  collected  in  the  bottom  of  this  pit,  comprising  twelve 
species  of  moUusks,  three  species  of  Bryozoa,  and  several  species  of  For- 
aminifera.  The  marks  in  Fig.  196  across  the  base  of  the  clay,  near  the 
blade  of  the  shovel  and  behind  the  man  in  the  photograph,  indicate 
the  horizon  where  the  fossils  occur.  (See  Figs.  200,  201.)  A  brick-clay 
pit  in  Lynn,  owned  by  Richard  Graham,  is  covered  by  a  cap  of  sand  and 
gravel  varying  from  six  to  ten  feet  in  depth,  below  which  is  a  bed  of  red- 
dish-gray brick-clay  eight  feet  in  thickness.  Below  this  clay  is  found 
blue  clay,  having  partings  of  fine  sand  every  few  inches,  and  containing" 
numerous  fossil  shells  of  Portlandia  Arctica.  A  foot  below  the  bottom 
of  the  pit  the  shells  of  Saxicava  Arctica  were  found  in  considerable 
number.  The  surface  of  the  soil  above  this  pit  is  about  twenty  feet 
above  mean  sea-level.  Birch  Pond  brook  runs  over  the  clay-beds  within 
a  few  feet  of  this  pit.  The  finding  of  fossils  in  this  leda-clay  establishes 
an  horizon  of  glacial  marine  clays  in  the  area  known  as  the  Boston 
basin.  This  leda-clay  is  of  a  deep  bluish-gray  color  when  moist,  but 
when  dry  it  becomes  a  light  gray.  Half  an  ounce  of  fine  quartz  sand  was 
obtained  from  eight  ounces  of  this  clay  when  washed  and  placed  in  a 
sieve,  ninety  mesh  to  an  inch.  The  residue,  a  fine  silty  mud,  when  well 
shaken  in  a  jar  of  water,  settled  to  the  bottom  in  fifteen  hours,  leaving" 
the  water  clear.  A  microscopical  examination  proved  this  clay  to  be 
composed  of  grains  of  quartz,  feldspar,  epidote,  calcite,  a  few  small 
plates  of  mica,  some  tourmaline  and  garnet  sand,  masses  of  chlorite  and 
kaolinized  feldspars,  several  shells  of  species  of  Foraminifera,  spicules 
of  sponges,  spines  of  echini,  and  some  diatoms. 


1 

i*^.      1  A 

> 

s               ^.^5d^^^ 

^^k^E 

irg-  r  z  - -_-^  -  r  r  r  -  -  - -_-i.-_--r- -  -  " 

A 

A 

Fig.  200.— CROSS-SECTION    OF  THE   VALLEY   OF   PORTER'S    RIVER,    DANVERS. 

I  .    Porter's  river.  2.    Edward  Carr  clay-pit. 

A.    Leda-clay.     B.    Reddish-gray  brick-clay,  with  sand  partings.     C.    Sand  and  soil.     T.    Boulder-till. 


1—  — 

3 


^8^      6  n 

14    6     1 

9 


1    "^1^ 


10 


Fig.  201.  — CROSS-SECTION    OF  THE    EDWARD    CARR   CLAY-PIT. 
Liberty  street,    Danvers. 
rick-clay  with  sand  partings.     C.    Sand  and  soil. 

2.  Pandora  olidrophom  Oouldiana,  Dall. 
4.   Thracia  myopsis  ? 
6.  Saxicaua  Aretica,  Loven. 
8.  Schizoporella  hyalina,  var.  Danuersi,  Sears. 
10.   Modiolaria  discors,  Loven. 


A.    Leda-clay.     B, 
I .  Portlandia  Aretica,  Gray. 
3.  Lyonsia  arenosa,  Morch. 
5.   Porttandia  fucida,   Loven. 
7.  Schizoporella  hyalina,  Linn. 
9.  Macoma  Baltica,  Linn. 


1 1 .  Modiolaria  IcBoigata,  Gray. 


I 

1 

Wssm 

M 

JO 

p^ 

1 

1 

1 

1 

HI 

1 

■ 

kfesHr^^l 

1 

1 

i 

■ 

9 

KV<. 

§ 

i 

■ 

^St 

1 

H 

^»« 

^Kj 

3 

Fig.   202.  — FOSSIL    STARFISH,    ASTERICANTHIAN    LINCKII,    MULLER. 

Found   in  the   Richard   Graham  clay-pit,    Lynn.     In  the  photograph  the  fossils  are  resting  in  a  tray 

measuring    I  8  I -2   by  2  I    I -2  inches. 


GLACIAL    MARINE    OR    LEDA-CLAYS  369 

The  leda-clay  contains,  in  certain  areas,  numerous  clay-stones  or 
clay  concretions,  many  of  which  have  fossils.  One  specimen  contained 
both  valves  of  Macoma  Baltica,  Linn,  and  another,  Modiolaria  Imvigata, 
Gray.  Clay  stones  with  one  or  both  valves  of  Portlandia  Arctica  are 
rather  common  in  the  clay-pit  on  Liberty  street,  Danvers.  Near  Elliott 
street,  Danvers,  the  lower  part  of  Folly  hill  slopes  into  the  valley  near 
the  bed  of  Frost  Fish  brook.  The  upper  part  of  the  bank  of  the  brook 
is  boulder-till,  which  reaches  to  the  top  of  the  hill,  and  beneath  it  is  found 
a  well-bedded  reddish-gray  clay.  In  the  bottom  of  a  deep  ditch  cut 
through  the  bank  the  blue  clays  occur.  Presumably  these  are  leda- 
clays,  although  no  fossils  have  been  found  in  them. 

The  upper  boulder-till  covering  these  clays  is  a  comparatively  loose 
yellowish-red  gravel  packed  hard  and  with  no  stratification  of  its  mem- 
bers. It  contains  many  well-glaciated,  scratched,  smoothed,  and  even 
rudely  polished  boulders  of  considerable  size.  Very  rarely  are  small 
boulders  and  pebbles  found  to  be  glaciated  in  this  form  of  till. 

In  September,  1903,  the  clay-beds  at  Danvers  were  again  visited 
and  clay-stones  were  collected,  some  of  which  contained  fossils,  the 
larger  number  being  Portlandia  Arctica,  Lyonsia  arenosa,  and  Saxicava 
Arctica}  Two  of  the  clay-stones  contain  an  annelid  worm-case  of 
an  undeterminable  species.  Later  in  the  month  the  Richard  Graham 
clay-pit  at  Lynn  was  inspected,  and  a  large  bed  of  fossil  starfish  was 
discovered.  (See  Fig.  202.)  Specimens  were  sent  to  Professor  A.  E. 
Verrill  of  New  Haven,  Conn.,  for  identification,  and  were  pronounced 
Asterias  stellionura,  Poiret;  Asteracanthion  Lincki,  Miihler.  He  wrote  as 
follows: 

"The  pedicellariae,  both  major  and  minor,  are  remarkably  well  pre- 
served and  very  characteristic.  On  the  Asteracanthion,  the  latter  form 
large  and  dense  clusters  around  all  the  spines,  and  they  are  unusually 
acute.     The  same  appears  in  your  fossils.     The  major  ones  are  very  large, 

1  Leda-clay  fossils  collected  by  the  author.     The    first   thirteen    species   were   found 
in  the  clay-pit  off  Liberty  street,  Danvers.     Number  fourteen  was  found  at  Lynn, 
(i)  Portlandia  Arctica,  Gray.  (8)  Macoma  Baltica,  Linn. 

(2)  Pandora  clidrophora,  Gouldiana,  Dall.  (9)   Modiolaria  discors,  Loven. 

(3)  Lyonsia  arenosa,  Morch.  (10)  Modiolaria  Imvigata,  Gray. 

(4)  Portlandia  Iticida,  Lroven.  (n)   Haminea  solitaria,  Say. 

(5)  Saxicava  Arctica,  Linn.  (12)   Cylichna  oryza,  Stimpson. 

(6)  Schizoporella  hyalina,  Linn.'?  (13)   Mactra  polynyma.  Stimpson. 

(7)  Schisoporella  hyalina.  vav.  Danversiensis,     (14)   Asteracanthion     Lincki,    Muller,    and 

Sears.  Trach. 


370  SUMMARY    OP    SUBSIDENCE    AND    ELEVATION 

ovate,  sub-acute,  especially  along  the  adambulacral  plates,  but  also  many 
on  the  dorsal  surfaces  as  in  your  examples.  Dorsal  plates  are  very  delicate 
and  form  a  slender  network.  Adambulacral  spines  are  small  and  slender, 
tapered,  acute,  and  a  large  tubed  spine  stands  singly  back  of  every  4th 
or  5th  plate  (sometimes  3d  or  4th)  as  in  yours.  In  all  of  these  characters 
and  others,  it  differs  from  A.  vulgaris.  A.  stellionura  I  first  took  off 
Cape  Sable,  Nova  Scotia,  on  the  American  side,  in  1877.  It  was  abun- 
dant in  30  to  60  fathoms,  some  of  them  growing  to  be  over  two  feet 
across.  It  is  a  very  arctic  species,  common  at  Spitzbergen  and  the  north- 
em  Norwegian  coasts.     This  discovery  is  of  much  interest." 

From  the  fact  that  living  specimens  of  these  fossils  are  to  be  dredged 
from  the  bottom  of  the  sea  at  the  present  time,  at  a  depth  of  thirty  to 
sixty  fathoms,  and  that  all  or  nearly  all  are  arctic  forms,  it  is  fair  to  pre- 
sume that  these  fossils  now  found  at  about  sea-level  formerly  lived  at 
a  depth  of  sixty  fathoms  on  the  bottom  of  the  glacial  sea.^  Such  assump- 
tion would  indicate  that  the  surface  of  the  land  was  formerly  three  hun- 
dred and  sixty  feet  lower  than  at  the  present  time,  a  subsidence  which 
would  cause  all  of  Essex  County  and  Eastern  Massachusetts  to  sink  be- 
neath the  sea.  Raised  sea  beaches  that  were  formed  as  the  land  was 
elevated  may  be  found  at  intervals  across  the  whole  of  Essex  County, 
and  toward  the  northwest  into  New  Hampshire  wherever  sand-plains 
and  gravel  ridges  occur.  The  sand-plains  at  Ipswich,  Rowley,  Byfield, 
Georgetown,  Groveland,  Lawrence,  and  Methuen  mark  various  raised 
beaches  where  the  waters  of  the  glacial  sea  stood  for  a  time  as  the  country 
was  being  elevated,  and  this  inland  sea  of  subsidence  will  account  for 
the  water-worn  and  rounded  pebbles  underlying  the  sand-plains,  show- 
ing them  to  be  ancient  sea  beaches.  It  also  accounts  for  the  water-dressed 
surfaces  of  many  outcropping  ledges  where  the  debris  of  erosion  has- 
been  removed,  leaving  the  bare  and  rounded  exterior.  Although  the 
longer  axes  of  these  ledges  are  parallel  to  the  line  of  glaciation  for  the 
region  in  which  they  occur,  there  are  many  examples  in  all  parts  of 
the  County  where  the  surface  seemingly  has  been  denuded  by  sea-action  in 
recent  times  and  yet  exhibits  no  attendant  features  that  would  account 
for  the  presence  of  the  sea  at  this  elevation. 

Summary  of  Subsidence  and  Elevation.  —  "The  typical  and  common 
species  of    Yoldia  Arctica  [the  Portlandia  Arctica  heretofore  mentioned] 

*  During  the  summer  of  1905,  the  author  found  in  the  leda  clay-pit  on  Liberty- 
street,  Danvers,  a  nearly  perfect  valve  of  a  species  of  Thracia,  measuring  17  mm.  long  and 
12  mm.  wide. 


Fig.   203.  — LONGHAM    BASIN,    NORTH    BEVERLY. 

Showing  escarpment  at  tlie  right  and   in  the   background. 


Fig.    204.  — GRAVEL-PIT    AT    LEGG'S    HILL,    SALEM,    SHOWING    KAME    GRAVELS. 


RECESSION    OF    THE    ICE-SHEET  373 

live  in  abundance  in  the  high  arctic  seas  at  depths  from  about  ten  to 
thirty  meters  [96  feet].  A  number  of  high  arctic  species  Uve  at  greater 
depths.  The  fauna  of  the  younger  Portlandia  clay  comprises  partly 
the  same  species  as  the  older,  but  in  other  varieties  some  new  forms  have 
also  supervened.  Thus,  for  instance,  Portlandia  Arctica  in  the  older  clay 
reaches  a  length  of  twenty-seven  to  twenty-eight  mm. ;  in  the  younger 
only  about  eighteen  mm.  Further,  it  is  to  be  remarked  that  this  clay 
must  have  been  deposited  at  some  greater  depth  than  the  older  clay,  as 
is  indicated  by  the  change  in  the  fauna."  ' 

The  Portlandia  Arctica  which  is  the  older  form,  and  now  collected 
at  Portland,  Maine,  and  Montreal,  Canada,  and  whose  length  is  27  mm. 
to  28  mm.,  accordingly  must  have  lived  on  the  sea  bottom  during  the  early 
part  of  the  Champlain  subsidence  when  the  land  had  been  depressed  not 
more  than  one  hundred  feet.  Portlandia  lucida,  Loven,  according  to 
Professor  Brogger,  occurs  in  the  younger  area  clays  or  deep-water  forms 
at  a  depth  of  at  least  two  hundred  and  forty  feet,  together  with  Portlandia 
Arctica  in  its  largest  forms,  i.e.,  8  mm.  to  14  mm.  The  P.  Arctica  and 
P.  lucida  found  in  Essex  County,  therefore,  are  forms  that  probably 
lived  on  the  leda-clay  when  the  subsidence  was  from  240  to  360  feet  in 
depth.  The  yotmger  Portlandia  clay  as  deposited  was  covered  up  in 
the  Terrace  period  by  the  brick  clays,  sands,  and  gravels. 

Recession  of  the  Ice-Sheet.  —  During  the  closing  era  of  the  great  ice 
period  in  the  Quaternary  age  the  whole  of  Essex  County  was  submerged 
beneath  the  sea.  Even  the  highest  ledges  and  the  tops  of  the  drumlins 
were  beneath  this  waste  of  waters  which  is  now  known  as  the  Champlain 
Sea  of  Subsidence.  The  land  surface  sank  at  least  three  htmdred  feet. 
As  the  surface  was  again  elevated,  the  waters  of  this  sea  when  disturbed 
by  storms  formed  lines  of  breakers  which  produced  well-defined  beach 
ridges  of  gravel  and  sand.  All  debris  was  washed  from  the  summits  of 
outcropping  ledges  and  drumlins,  many  of  which  were  channeled  and 
left  thickly  strewn  with  large  boulders. 

Post-Glacial  erosion  may  be  seen  in  many  parts  of  the  County.  In 
the  western  part  of  Georgetown  the  Parker  river  has  cut  a  passage  to  the 
sea  through  numerous  ridges  and  sand-plains,  and  this  is  true  of  all  the 
streams  in  the  County.  The  Merrimac  river  with  each  recurring  spring 
season  cuts  into  the  bases  of  the  drumlins  along  its  course,  and  carries  the 
debris  to  the  delta  at  its  mouth.     A  fine  example  of  such  erosion  may  be 

>  Professor  W.  G.  Brogger:  Glacial  Fauna  of  Norway  and  Late  Glacial  and  Post- 
Glacial  Changes  of  Level  in  the  Kristiania  Region. 


3  74  RECESSION    OF    THE    ICE-SHEET 

seen  at  North  Beverly,  north  of  Dodge  street,  where  Longham  brook  has 
cut  a  channel  in  a  sand-plain  for  a  distance  of  nearly  a  mile,  leaving  an 
escarpment  from  fifteen  to  twenty  feet  in  height.  Corrosion  has  widened 
the  valley,  which  in  the  adolescent  stage  of  the  stream  was  grassed  over 
and  probably  covered  with  forest  trees.  The  Salem  and  Beverly  Water 
Boards  took  advantage  of  this  escarpment  and  ancient  stream-cutting, 
and  by  building  a  dam  created  an  artificial  lake  known  as  "the  Long- 
ham  basin,"  which  serves  the  purpose  of  an  auxiliary  water  supply.  (See 
Fig.  203.) 

Sea-worn  gravels  with  round  cobble-stones  are  a  general  feature  of 
gravel-beds  about  the  County.  (See  Fig.  204.)  These  gravels  contain 
calcitmi  lime  in  solution,  which,  when  gravel-beds  are  opened,  becomes 
carbonized,  and  cements  the  small  particles  of  gravel  together  in  a  form 
of  conglomerate,  and  often  produces  a  crust  on  the  outside  of  pebbles 
and  boulders.  The  presence  of  this  lime  indicates  that  there  may  have 
been  shell-bearing  moUusks  in  the  gravel  and  that  the  shells  have  been 
dissolved  by  carbonic  acid  percolating  from  the  surface.  Occasionally  a 
large  boulder  is  found  in  these  gravels,  having  been  dropped  from  the 
bottom  of  floating  ice. 


^,ri:^/u^^ 


Fig.   205.  —  PORTLAND/A    ARCTICA,    GRAY. 

From  the   Peabody   Pottery  clay-pit,    Purcliase  Street,   Da 


Ti(^\    E-Klci\cte(.  |!V0-\Ai.  ^■\-\uMv\.6\VC.t'^'V^'»^*-^"^'^' 


^</lSlf 


[::!*^*~ 


:> 


Fig.  206.    GLAQAL  MARINE  FOSSILS  FOUND  IN  LEDA-CLAY  IN  THE  EDWARD 
CARR  BRICK  CLAY-PIT,  LIBERTY  STREET,  DANVERS. 

No.  I.  Portlandia  Arctica,  Gray,  a  typical  specimen  of  the  largest  size,  iij  mm.  long 
8  mm.  wide. 

Nos.  la  and  ib.  Portlandia  Arctica,  Gray,  greatly  enlarged,  showing  hinge  area  with 
teeth  ;  la,  upper  hinge  ;  ib,  lower  hinge. 

No.  2.     Pandora  olidrophora,  Goiildiana,  Dall.,  23  mm.  long,  15  mm.  wide. 

No.  3.    Modiolaria  discors,  Loven.,  10  mm.  long,  6  mm.  wide. 

No.  4.    Saxicava  A?-ctica,  Linn.,  23^  mm.  long,  11  mm.  wide. 

No.  5.    Lyonsia  arenosa,  Morch.,  19  mm.  long,  11  mm.  wide. 

No.  5a.    Mactra  luteola,  Loven.,  ?   in  a  clay  stone. 

No.  6.     Cylichna  oriza,  Stimpson,  4J  mm.  long,  2^  mm.  wide. 

No.  7.    Hamijiea  solitaria,  Say.,  2  mm.  long,  ij  mm.  wide. 

No.  8      Schizoporella  hyalina,  Linn.,  cluster  3  mm.  long,  3  mm.  wide. 

No.  9.     Schizoporella  hyalina,  var.  Danversimsis,  Sears,  elongated  colony,  i,\  mm.  lono- 


CHAPTER  XII 

PALEONTOLOGY   OF   THE     CAMBRIAN    ROCKS 

Numerous  markings  in  the  limestone  at  East  point,  Nahant,  were 
discovered  in  1887,  by  the  author,  and  for  the  first  time  considered  to  be 
fragments  of  fossils.  The  geologists  of  Massachusetts  did  not  coincide, 
even  after  a  piece  of  the  limestone  had  been  ground  to  a  flat  surface  and 
polished,  and  the  fossil  fragments  thickly  scattered  over  the  surface  had 
been  closely  inspected.  The  polished  specimen  was  then  placed  in  the 
geological  cabinet  at  the  museum  of  the  Peabody  Academy  of  Science 
in  Salem.  In  1889,  Dr.  Aug.  F.  Foerste,  the  eminent  paleontologist, 
then  a  student  at  Harvard  University,  collected  a  series  of  these  fossils, 
and  published  a  paper  in  the  Proceedings  of  the  Boston  Society  of  Nat- 
ural History  (Vol.  XXIV,  pp.  261-263),  in  which  he  identified  the  species 
discovered  in  1887  as  HyoUthes  inequilateralis ,  a  type  distinct  from  Hyo- 
Uthes  princeps.  The  name  inequilateralis  was  not  generally  accepted  for 
the  species,  and  princeps,  Billings,  has  been  assigned.  Since  1889  the 
author  has  collected  several  himdred  specimens  and  fragments  of  fossils 
in  the  Cambrian  limestones  at  Nahant,  many  of  them  being  new  to  Essex 
County,  and  all  of  which  are  now  preserved  in  the  geological  cabinets  of 
the  Peabody  Academy  of  Science.  For  a  detailed  accotmt  of  the  fossils 
shown  in  Fig.  209,  with  the  exceptions  of  Scenella  and  Fordilla,  the  reader 
is  referred  to  a  paper  by  Dr.  A.  W.  Grabeau  on  the  "Paleontology  of  the 
Cambrian  Terrenes  of  the  Boston  Basin,"  published  in  "  Occasional  Papers 
of  the  Boston  Society  of  Natural  History,"  Vol.  I,  part  III,  pp.  605-656. 
Dr.  Grabeau  received  the  fossils  used  in  the  preparation  of  his  paper  with 
the  understanding  that  his  material  should  also  be  available  for  this  work. 

Outcrops  of  Cambrian  fossiliferous  limestone  occur  on  the  extreme 
outer  portion  of  East  point,  Nahant,  where  the  fossil  horizon  occurs  from 
ten  feet  above  mean  sea-level  and  extends  twelve  feet  up  the  face  of  the 
cliff.  The  beds  are  interstratified  limestone,  slate,  and  chert  —  an  im- 
pure quartzite.  Here  fossils  of  HyoUthes,  several  species  of  brachipods 
and  Stenotheca,  have  been  found.  Another  outcrop  of  this  fossiliferous 
limestone  occurs  on  the  ocean  side  opposite  "MaoHs  Spring,"  so-called, 

380 


Fig.  207.    GLACIAL  MARINE  FOSSILS  JFOUND  IN  LEDA-CLAY  AT  DANVERS. 

No.  I.  A  cleavage  piece  of  clay  with  fossil  Portlandia  Arctica  in  position  on  the  natural 
bedding  of  the  clay.  Reduced  \.  From  the  Peabody  Pottery  clay  pit,  Purchase  street, 
Dan  vers. 

No.  2.  Modiolaria  lavigata,  Gray,  on  a  clay  stone  ;  length,  28  mm.,  width,  26  mm.  From 
Edward  Carr's  clay  pit.  Liberty  street,  Danvers. 

No.  3.  Macoma  Baltica,  Linn.,  on  a  clay  stone  ;  length,  23^  mm.,  width,  23^  mm.  From 
Edward  Carr's  clay  pit,  Liberty  street,  Danvers. 


384  PALEONTOLOGY   OP   THE   CAMBRIAN    ROCKS 

where  HyoUthes  princeps  occurs,  specimens  measuring  four  inches  long 
and  one  inch  across  the  basal  section  having  been  collected.  Still  another 
outcrop  occurs  on  the  Lynn  harbor  side  of  Bass  point,  where  the  beds  are 
all  below  high  tide  or  sea-level.  The  horizon  is  about  eighteen  inches 
thick,  from  top  to  bottom.  This  outcrop  is  near  the  causeway  leading 
from  Little  Nahant  to  Bass  point  in  a  bank  by  the  roadside.  The  fossils 
at  this  locality  are  Lower  Cambrian  and  are  largely  HyoUihellus  micans, 
Billings ;  Stenotheca  abrupta,  Shaler  and  Foerste ;  Scenella  Rohinsoni,  Sears 
(the  latter  species  named  for  John  Robinson  of  Salem) ;  Orthotheca  cylin- 
drica,  Grabeau;  and  HyoUthes  impar,  Ford. 

Beside  Rowley  Bridge  street,  Topsfield,  on  the  Peterson  farm,  there 
is  a  series  of  outcrops  of  slate,  blue  limestone,  chert,  and  ferruginous 
quartzite.  In  the  limestone  and  the  reddish  slates  are  found  fossil  casts 
of  an  annelid,  4  mm.  in  diameter  and  30  mm.  in  length.  The  blue  lime- 
stone, which  is  probably  Middle  Cambrian,  contains  numerous  minute  to 
microscopic  fossil  lamellibranch  shells  and  a  sponge,  Ethmophyllum,  having 
only  six  septa.  Ford's  specimens  have  from  eighteen  to  twenty-one  septa. 
In  the  roadway  east  of  Archelaus  hill,  West  Newbury,  occurs  a  series  of 
outcrops  of  red  limestone,  slate,  and  quartzite.  The  limestone  contains 
numerous  fragments  of  HyoUthes  and  other  Cambrian  fossils.  On  the  west 
bank  of  Batchelder's  brook,  east  of  Clay  lane  in  Rowley,  there  is  another 
outcrop  of  Cambrian  rocks  where  the  surface  is  nearly  all  a  chert,  which 
contains  fragments  of  HyoUthes.  While  digging  a  well  at  the  Daniel's 
wagon  factory  at  Chaplinville,  Rowley,  a  ledge  was  encountered  which 
proved  to  be  a  red  slate  interstratified  with  limestone  from  which  broken 
pieces  of  HyoUthes  fossils  were  taken.  Outcrops  of  this  series  of  Cambrian 
rocks  may  be  seen  on  both  sides  of  the  Boston  and  Newburyport  turnpike 
at  various  points  between  Chaplinville  and  Glen  Mills.  The  city  ledge  in 
South  Lawrence  is  also  a  fossiliferous  Cambrian  rock  of  metamorphosed 
limestone  interstratified  with  quartzite  and  slate.  In  a  railroad  cutting  at 
the  base  of  Paper  Mill  hill  in  West  Peabody  there  are  outcrops  of  chert, 
limestone,  and  slate,  identical  in  character  with  the  Cambrian  fossiliferous 
rocks  of  Nahant,  and  although  fossils  have  not  as  yet  been  discovered, 
without  doubt  the  outcrops  are  of  the  Cambrian  period.  On  the  south  side 
of  Chestnut  street,  Lynnfield  Centre,  are  numerous  outcrops  of  white  quart- 
zite, blue  slate,  and  limestone,  which  contain  fossils,  probably  species  of 
annelids  and  fucoids,  which  Dr.  Grabeau  was  unable  to  identify.  These 
outlying  outcrops  have  not  been  examined  critically,  and  a  knowledge 
of  their  fossils  is  confined  to  a  very  hasty  inspection. 


2a, 


2b 2e 


2f 


3b 


3o 


20     2g 


^O 


231 


^ 


5a  S^ 


o 


Si 


Cx 


?d 


I2a 


Fig.  208.    CAMBRIAN  FOSSILS  FROM  NAHANT  AND  JEFFREY'S  LEDGE. 

No.  2.     Hyolithes  princeps,  Billings. 

No.  2a.     Dorsal  side  of  a  young  individual  showing  forward  curving  strise  and  lip. 

No.  2b.     Fragment  of  a  specimen  showing  dorsal  side  and  cross-section.    Enlarged. 

No.  2C.  Cross-section  referred  to  this  species  obliquely  cut.  Enlarged  from  10  mm.  to 
13J  mm. 

No.  2d-e.     Sections  of  large  specimens  from  outside  of  Maolis  spring,  Nahant. 

No.  2f-h.  Various  cross-sections,  the  variations  in  outline  being  due  chiefly  to  obliquity 
of  cut.     Enlarged. 

No.  3.    Hyolithes  excellens,  Billings. 

No.  3a.     Dorsal  side  of  specimen  described.     Natural  size. 

No.  3b.     Cross-section  of  same. 

No.  3c.    Cross-section  of  a  specimen  of  this  species.     Natural  size. 

No.  4.    Hyolithes  Americamcs,  Billings. 

No.  4a.  Dorsal  view  of  the  specimen  described.  The  upper  part  is  broken  away. 
Enlarged. 

No.  5.    Hyolithes  Sea?-si,  Grabeau. 

No.  5a.     Cross-section  of  the  largest  specimen  known.    Natural  size. 

No.  5b.    Group  of  cross-sections.    Natural  size. 

No.  6.    Hyolithes  communis,  Billings.     Cross-section  showing  normal  form. 

No.  7.    Hyolithes  impar.  Ford. 

No.  7a.     Normal  shell  with  oval  cross-section.    Enlarged. 

No.  7b.     Fragment  (restored)  with  cross-section.    Enlarged. 

No.  7C.     Cross-section,  enlarged. 

No.  8.     Orthotheca  cylindrica,  Grabeau. 

No.  8b.    Fragment  of  a  large  specimen.    Enlarged. 

No.  8d.     Cross-section  of  the  invaginated  specimens.    Enlarged. 

No.  8g,     Small  curved  specimen  which  may  be  of  this  species.     Enlarged. 

No.  g.     Orthotheca  Emmonsi,  Ford. 

No.  ga.     Dorsal  view  of  a  specimen  showing  faint  concavity.     Natural  size. 

No.  9b.     Characteristic  cross-section. 

No.  gc.     Cross-sections  of  invaginated  shells. 

No.  gd.    Ventral  view  of  a  specimen  with  cross-section. 

No.  12.  Hyolithelhis  micans,  Billings.  A  fragment  referred  to  this  species  from  a  red 
limestone  boulder  at  Nahant.    Boston  Society  of  Natural  History,  Cat.  No.  ii,g66. 

No.  13.  Longitudinal  section  of  a  hyolithid  (?J  showing  two  septa.  From  blue  limestone 
at  Jeffrey's  ledge.     Enlarged. 

No.  14.  Longitudinal  section  of  an  undetermined  shell.  From  blue  limestone  at  Jeffrey's 
ledge.     Enlarged. 

No.  15.  Longitudinal  section  of  a  Salterella  (?).  From  blue  limestone  at  Jeffrey's  ledge. 
Enlarged. 


388  PALEONTOLOGY    OF    THE    CAMBRIAN    ROCKS 

Recent  experiments  with  a  weak  solution  of  muriatic  acid  upon  the 
white  limestone  from  East  point,  Nahant,  resulted  in  etching  out  perfect 
specimens  of  Stenotheca  abrupta,  Foerste  and  Shaler;  Ohellela  crassa,  Hall; 
Orthotheca  cylindrica,  Grabeau ;  Hyolithes  princeps,  Billings ;  Hyolithes  Amer- 
icanus,  Billings;  Hyolithes  Searsi,  Grabeau;  Hyolithes  commtinis,  Billings; 
Hyolithes  impar,  Ford,  and  an  interior  valve  of  Fordilla  Troyensis,  Walcott. 
Two  very  perfect  casts  of  shells  of  Stenotheca,  with  six  corrugations,  have 
been  found.  They  are  nearly  vertical.  One  measures  4  mm.  across  the 
base  and  3  mm.  in  height,  and  has  been  provisionally  named  Stenotheca 
abrupta,  Shaler  and  Foerste,  variety  N ahantiensis .  The  second  measures  3 
mm.  across  the  base  at  its  narrowest  part,  and  is  3  mm.  in  height.  This 
shell  has  been  named  Stenotheca  abrupta,  Shaler  and  Foerste,  variety 
Foerstei,  in  honor  of  Dr.  Aug.  F.  Foerste,  the  first  to  describe  species  of 
fossils  in  the  County.  A  specimen  of  Hyolithes  has  been  found  resem- 
bling Hyolithes  princeps,  Billings,  but  the  cross-section  is  in  the  form  of  a 
sexta  and  entirely  different  from  the  Billings  type.  This  shell  has  been 
named  Hyolithes  princeps,  Billings,  variety  Pingreei,  in  honor  of  Mr. 
David  Pingree  of  Salem,  Mass. 

The  more  siliceous  limestone  on  the  Lynn  harbor  side  of  Nahant,  when 
similarly  treated,  resulted  less  successfully,  for  the  acid  destroyed  the 
fossils,  and  usually  left  only  casts.  However,  this  limestone  has  produced 
in  abundance  minute  to  ordinary  specimens  of  Hyolithes  micans,  Bill- 
ings, and  Orthotheca-  cylindrica,  Grabeau,  of  large  size  and  in  considerable 
n-umber.  One  piece  of  cherty  limestone  contained  three  nearly  perfect 
specimens  of  Hyolithes  communis,  Billings;  and  another,  a  doubtful  speci- 
men of  Hyolithes  princeps  and  a  Stenotheca  without  corrugations.  The 
dark  blue  limestone  from  the  outcrop  in  Topsfield  is  so  homogeneous  on 
a  freshly  broken  surface  that  it  is  impossible  to  discern  recognizable  spe- 
cies of  fossils.  These  only  may  be  noted  in  sections  ground  thin  enough 
to  permit  light  to  pass  through  the  specimen,  when  numerous  fossils 
are  revealed  in  every  piece  of  the  stone.  These  fossils  comprise  minute 
brachiopods,  lamellibranch  shells,  fossil  sponges,  Hyolithes,  etc. 


Fig.  209.    CAMBRIAN  FOSSILS  FROM  TOPSFIELD  AND  NAHANT. 

No.  I.  Longitudinal  section  of  an  Ethmophylhim  rarui/i,  Ford.  From  the  blue  lime 
stone  on  the  Peterson-Towne  farm,  Topsfield. 

No.  2.  Cross-section  of  an  Ethmophylluui  rarum,  Ford.  Showing  six  septa.  From 
same  locality. 

No.  3.  Cross-section  of  an  Ethiuophylhim,  with  septa  crushed  and  broken.  From  same 
locality. 

No.  4.     Section  of  the  shell  of  a  species  of  lemellibranch.     From  same  locality. 

No.  5.  Section  of  the  shell  of  a  species  of  lemellibranch,  showing  hinge  area  cut 
obliquely.     From  same  locality. 

No.  6.  Section  of  the  shell  of  a  species  of  lemellibranch,  showing  the  hinge.  From 
same  locality. 

No.  7.     Section  of  the  shell  of  a  brachiopod  ?.     From  same  locality. 

No.  8.     Cast  of  an  annelid  boring?     From  same  locality. 

No.  9.  Shell  of  Orthotheca  cyliiidrica.  From  white  limestone,  Lynn  harbor  side  of 
N  ah  ant. 

No.  10.  Shell  of  Stenotheca  abrupta,  Shaler  and  Foerste  ?  Forma  Nahanti,  Sears. 
From  white  limestone,  East  Point,  Nahant. 

No.  II.  Shell  of  Stejiotheca  abrupta,  Shaler  and  Foerste?  Forma  Foerstei,  Sears. 
From  white  limestone.  East  Point,  Nahant. 

No.  12.  Cast  of  shell  of  Stenotheca  abrupta,  Shaler  and  Foerste.  From  white  limestone, 
Lynn  harbor  side  of  Nahant. 

No.  13.     Cast  of  shell  of  Scenella  Robinsoni,  Sears.     From  Lynn  harbor  side  of  Nahant. 

No.  14.     Scenella  varians,  Walcott.     From  white  limestone.  East  Point,  Nahant. 

No.  15.  Fordilla  Troyensis,  Walcott.  Cast  of  the  interior  of  the  right  valve  enlarged. 
From  white  limestone,  East  Point,  Nahant. 

No.  16.  Hyolithes  princeps,  Billings.  Forma  Pingi'eei,  Sears.  From  East  Point, 
Nahant. 


Appendix  A 
SURFACE   AREAS 


Table  showing  number  of  square  miles  and  acres  of  territory  in  each 
of  the  seven  cities  and  twenty-eight  towns  in  Essex  County,  Massachu- 
setts, in  the  year  1903,  together  with  the  areas  covered  by  water,  swamps, 
and  highways. 


Cities  and  Towns  in  the  Codnty 


Amesbury 

Andover      

Beverly 

Boxford 

Bradford 

Danvers 

Essex 

Georgetown 

Groveland 

Gloucester 

Hamilton 

Haverhill 

Ipswich 

Lawrence 

Lynn 

Lynnfield 

Merrimac 

Methuen      

Middleton 

Manchester 

Marblehead 

Newburyport 

Newbury         

North  Andover 

Peabody      

Rockport 

Rowley 

Salem 

393 


Area  in  Square 
Miles 

Area  in  Acres 

14 

8,960 

33 

21,120 

20 

12,800 

24 

15,360 

7 

4,480 

14 

8,960 

18 

11,520 

II 

7,040 

7 

4,480 

34 

21,760 

IS 

9,600 

28 

17,920 

41 

26,240 

8 

S,I20 

12 

7,680 

10 

6,400 

9 

5,760 

24 

15.360 

16 

10,240 

9 

5.760 

6 

3.840 

18 

11,280 

27 

17,280 

28 

17,920 

17 

10,880 

7 

4,480 

19 

12,160 

9 

5.760 

394 


APPENDIX 
SURFACE    AREAS.     (Continued.) 


Cities  and  Towns  in  the  ConNTV 


Saugus  .  .  . 
Salisbury  .  . 
Swamp  scott  . 
Topsfield  .  . 
Wenham .  .  . 
West  Newbur}' 
Nahant  .  .  . 
Totals 


7,680 

12,500 

1,920 

8,320 

5. 760 

g,6oo 

640 

3SS.840 


Tidal  marsh 

Tidal  river  valleys  and  bays 

Peat  swamps  having  a  depth  of  6  to  15  feet  .  .  .  . 
Fresh-water  meadows  covered  by  water  in  the  spring 
Parks  and  roads  (in  1898) 


Total 

Assessable  land  consisting  of  village  and  city  sites,  uplands,  woods, 
and  tillage 


ACEESi 
21,789 
18,000 
16,500 
16,500 

8,000 

80,789 
275.051 


Appendix  B 


ELEVATION  AND   LOCATION   OF   THE   DRUMLINS   IN   ESSEX 
COUNTY 


Archelaus  hill,  West  Newbury 

Asleb  hill,  North  Andover 

Ayer's  hill,  Haverhill  and  Methuen    .    .    .    . 

Bald  hill,  Boxford 

Bald  Pate  hill,  Georgetown 

Bare  hill,  Danvers 

Bare  hill,  Methuen 

Bare  hUl,  Topsfield 

Bartholomew's  hill,  Ipswich 

Batt's  hill,  Salisbury 

Beach  hill,  Salisbury 

Bear  hill,  Merritnac . 

Bear  hill,  North  Andover 

Berry's  hill,  Boxford 

Blaisdell's  hill,  Merrimac 

Boston  hill.  North  Andover 

Brake  hill,  West  Newbury 

Brandy  Brow  hill,  Merrimac 

Brown's  hill,  Hamilton 

Brown's  hill,  Ipswich 

Brown's  hill.  South  Groveland 

Browne's  hill,  Groveland 

Burying  Ground  hill,  Amesbury 

Bush  hill,  Ipswich 

Bush  hill,    Merrimac 

Castle  hill,  Ipswich 

Cheney's  hill,  Groveland 

Clay  Pits  hill.  North  Andover 

Cook's  hill,  Danvers      

Corliss'  hill,  Haverhill 

Crane  Neck  hill.  West  Newbury 

Crowninshield  hill,  Topsfield 

Cutler's  hill,  Hamilton 

Elliott's  hill,  Haverhill 

395 


Feet 
240 
240 
320 
240 

240 
360 
140 
180 
160 
200 
240 
360 
200 
180 
380 
240 
258 
180 
100 
220 
200 
180 
140 
260 
140 
140 
240 
200 
280 

260 
140 
220 


396 


APPENDIX 


ELEVATION  AND  LOCATION  OF  THE  DRUMLINS  IN  ESSEX  COUNTY      (Continued) 


Fair  Maid's  hill,  Danvers  .... 
Farm  hill,  West  Newbtiry  .... 
Femcroft,  or  Preston's  hill,  Danvers 

Folly  hill,  Danvers 

Foster's  hill.  North  Andover  .    .    . 

Golden  hill,  Haverhill 

Goodale's  hill,  Peabody 

Grape  hill,  Salisbury  and  Seabrook 

Great  hill,  Haverhill 

Great  hill,  Topsfield      

Hall's  hill,  Amesbury 

Hardy's  hill,  Groveland 

Harris'  hill,  Methuen 

Hathome  or  Asylum  hill,  Danvers 

Head's  hill,  Bradford 

Heartbreak  hill,  Ipswich  .... 
Highlands  hill,  Merrimac     .... 

Hill  Dale,  Haverhill      

Holt's  hill,  Andover      

Hopkins'  hill,  Groveland      .... 

Howlett's  hill,  Topsfield 

Huckleberry  hill,  Haverhill.    .    .    . 

Hunslow  hill,  Rowley 

Hunting  hill,  Haverhill 

Hutchings'  hill,  Groveland  .... 
Ilsley's  hill.  West  Newbury  .  .  . 
Indian  hill,  West  Newbury      .    .    . 

Jewett's  hill,  Rowley 

Job's  hill,  Haverhill      

Kimball's  hill,  Haverhill  .... 
Kimball's  hill,  North  Beverly.  .  . 
King's  hill.  West  Peabody  .... 

Lindall  hill,  Danvers 

Little  Neck,  Ipswich 

Little  Turner's  hill,  Ipswich    .    .    . 

Long  hill,  Georgetown      

Long  hill,  Merrimac       

Long  hill,  West  Gloucester  .  .  . 
Long  hill,  West  Newbury    .... 

Lone  Tree  hill,  Methuen 

Lummus'  hill,  Hamilton 


Feet 

i6o 

200 

i8o 

200, 

240 

253 

160 
240 

340 

240 
200 

180 
300 
280 

272 
160 
270 
240 
400 

235 
180 

240 

180 
180 

200 
200 

180 

160 
260 
240 
160 
200 
120 

80 

140 
200 
120 
160 
200 

180 

140 


APPENI 


397 


ELEVATION  AND  LOCATION  OF  THE  DRUMLINS  IN  ESSEX  COUNTY      (Continued) 


Mears'  hill,  Essex      

Meeting-house  hill,  Methuen    .    .    .    . 

Mills'  hill,  North  Andover 

Moulton's  hill,  Hamilton      

Mussey  hill,  Ipswich 

Nichols'  or  Dale's  hill,  Danvers      .    . 
North  Ridge,  Jeffrey's  Neck,  Ipswich 

Old  Town  hill,  Newbury      

Osgood's  hill,  North  Andover      .    .    . 

Ox  Pasture  hill,  Rowley 

Paper  Mill  hill.  West  Peabody    .    .    . 

Parsonage  hill,  Haverhill 

Perkins'  hill,  Essex 

Perkins'  hill,  Topsfield 

Perry's  hill,  Groveland 

Pigeon  hill,  Rockport 

Pine  hill,  Andover 

Pine  hill,  Lynnfield 

Pine  hill.  South  Groveland      .    .    .    . 

Pingree's  hill,  Topsfield 

Pipe  Stave  hill.  West  Newbury  .    .    . 
Plover  hill.  Great  Neck,  Ipswich     .    . 

Pole  hill,  Andover 

Pond  hill,  Amesbury     ....... 

Powder  House  hill,  Amesbury     .    .    . 
Powder  House  hill,  Methuen   .    .    .    . 

Po wow  hill,  Amesbury 

Prospect  hill,  Lawrence 

Prospect  hill,  Rowley 

Putnam's  hill,  Danvers 

Red  Oak  hill,  Merrimac 

Red  Root  hill,  Hamilton 

Reservoir  hill,  Lawrence      

Reservoir  hill.  South  Groveland.    .    . 

Ring's  hill,  Amesbury 

Russell's  hill,  North  Andover      .    .    . 

Sagamore  hill,  Hamilton      

Saltonstall's  hill,  Haverhill      .    .    .    . 

Sargent's  hill,  Amesbury      

School  House  hill,  North  Andover.    . 
Scotland  hill,  Methuen 


Feet 

i6o 
220 
300 
100 
180 
200 
120 
140 
380 
180 
200 

233 
180 
200 
180 
180 
300 
200 
100 
260 
180 
120 
140 
200 
140 
200 

Zl° 
140 
264 
200 
308 
160 
140 
240 
280 
300 
200 
290 
240 
200 
280 


398 


APPENDIX 


ELEVATION  AND  LOCATION  OF  THE  DRUMLINS  IN  ESSEX  COUNTY     (Continued) 


Scott's  hill,  Ipswich      

Silver  hill,  Haverhill 

Smith's  hill,  Peabody 

Solomon's  hill,  Danvers 

South  Scotland  hill,  Haverhill 

Spofford's  hill,  Boxford 

Steep  hill,  Castle  Neck,  Ipswich 

Stiles'  hill,  Boxford 

Sutton's  hill.  North  Andover 

Swan's  hill,  Groveland 

The  hill,  northwest  of  Kenoza  lake,  Haverhill 

Thomas'  hill,  Peabody 

Tilton's  hill,  East  Ipswich 

Timber  hill,  Ipswich 

Titcomb's  hill,  Merrimac      

Town  Farm  hill,  Methuen 

Town  hill,  Ipswich 

Turkey  hill,  Haverhill 

Turkey  hill,  Ipswich 

Turkey  hill,  Merrimac 

Turkey  hill,  Newburyport 

Turner's  hill,  Ipswich 

Tyler's  hill.  North  Andover 

Upton's  hill,  Peabody 

Vineyard  hill,  Hamilton 

Walden  hill,  Peabody 

West  Meadow  hill,  Haverhill 

Whipple's  hill,  Danvers 

White's  hill,  Essex 

Whittier's  hill,  Amesbury 

Whittier's  hill,  Haverhill 

Wilkins'  hill,  Middleton 

Will's  hill,  Middleton 

Willow  Dale  hill,  Hamilton 

Weir  hill,  North  Andover 

Wood  hill,  Andover 

Woodbury's  hill,  Hamilton 

Woodchuck  hill.  North  Andover , 


Feet 

i8o 

278 
180 
280 
320 
220 
120 
300 
220 
220 
320 
220 
160 
140 
220 
320 
160 
250 
240 
240 
140 
260 
200 
200 
120 
220 

337 
160 
160 
200 

2SS 

160 

220 
200 
300 
340 
120 
320 


Whole  number  of  drumlins  in  Essex  County,   193. 
ing  names,  157. 


Number  of  drumlins  hav- 


Appendix  C 


ELEVATION   AND   LOCATION  OF   BED-ROCK  HILLS,  BARE   OR  WITH 
A  THIN  COATING  OF    DRIFT  UPON  THEM. 


Elevation 

ABOVE  Mean 

Sea-level 


Bald  hill,  Centreville,  Beverly,  a  nearly  bare  ledge  of  akerite  syenite.    . 

Castle  hill,  Saugus,  a  nearly  bare  ledge  of  rhyolite 

High  Rock,  Lynn,  a  nearly  bare  ledge  of  rhyolite 

Mount  Spicket,  Lynn,  a  nearly  bare  ledge  of  hornblende  granite     .    .    . 

Legg's  hill,  Salem,  a  bare  ledge  of  hornblende  diorite 

Castle  hill,  Salem,  a  nearly  bare  ledge  of  hornblende  diorite 

Poole's  hill,  Rockport,  a  nearly  bare  ledge  of  hornblende  granite  .  .  . 
Railcut  hill,  Gloucester,  a  nearly  bare  ledge  of  hornblende  granite  .  . 
Thompson's  hill.  West  Gloucester,  a  nearly  bare  ledge  of  hornblende 

granite 

Moses'  hill,  Manchester,  a  nearly  bare  ledge  of  hornblende  granite  .  . 
Wyman's  hill,  Manchester,  a  nearly  bare  ledge  of  hornblende  granite     . 

Mount  Ann,  Gloucester,  a  bare  ledge  of  hornblende  granite 

Uptack  hill,  Groveland,  an  early  bare  ledge  of  Cambrian  sedimentary  rock 
Ship  Rock,  Peabody,  a  boulder  upon  a  bed-rock  of  hornblende  granite 
Mount  Pleasant,  Peabody,  a  nearly  bare  ledge  of  hornblende  granite 
Robin  Rock,  South  Lynnfield,  a  hornblende  granite  quarry 


I20 

280 
185 
278 
140 

65 
180 
180 

220 
180 
200 
240 
220 
160 
140 
140 


Appendix  D 


LAKES   AND   PONDS   IN   ESSEX   COUNTY 


There  are  eighty  lakes  and  ponds  in  Essex  County,  including  dammed 
streams  producing  mill-ponds  and  water-supply  reservoirs.  The  number 
of  acres  covered  by  each  pond  in  the  following  list  is  closely  approximated, 
as  no  exact  survey  has  ever  been  made.  Four  quite  distinct  benches  or 
levels  extend  across  the  County  on  which  nearly  all  of  the  lakes  and  ponds 
are  situated.  The  first  being  from  three  or  four  feet  to  ten  feet  above 
sea-level;  the  second,  about  forty  feet  above  sea-level;  the  third,  from 
sixty  to  eighty  feet  above  sea-level;  and  the  fourth,  from  one  hundred 
to  one  hundred  and  forty  feet  above  sea-level.  It  has  not  seemed  de- 
sirable to  enumerate  in  this  list  all  of  the  mill-ponds  in  the  County,  many 
of  which  are  no  longer  in  use,  while  others  are  being  formed  from  year  to 
year. 


Name  of  Pond  . 


Height  above 

Mean 

Sea-Level 

Area 

Fea 

Acres 

3  or  4 

20 

5 

variable 

6 

18 

less  than  2 

25 

40 

70 

40 

170 

40 

43 

40 

35 

40 

25 

40 

30 

40 

35 

40 

20 

40 

60      • 

40 

20 

45 

8i 

40 

250.6 

40 

3 

40 

8 

80 

35 

40 

56 

Niles'  pond,  East  Gloucester   .    . 

Phillips'  pond,  Swampscott 

Bear  pond,  Nahant 

Clark's  pond,  Jeffrey's  Neck.  Ipswich    .    .    . 

Cape  pond,  Rockport 

Chebacco  lake,  Essex 

Beck's  pond,  Hamilton 

Bound  pond,  Hamilton 

Gravel  pond,  Hamilton 

Coy's  pond.  East  Wenham 

Pleasant  pond,  Wenham  and  Hamilton     .    . 

Beaver  pond,  Beverly 

Norwood's  pond,  Beverly 

Muddjr  pond,  Wenham 

Cedar  pond,  Wenham 

Wenham  lake,  Beverly  and  Wenham     .    .    . 

Legg's  Hill  pond,  Salem 

Glenmere  or  Floating  Bridge  pond,  Lj'nn     . 

Wyoma  lake,  Lynn 

Wenuchus  lake  or  Flax  pond,  Lynn  .    .    .    . 

400 


APPENDIX 


401 


LAKES    AND    PONDS    IN    ESSEX    COUNTY     (Continued) 


Name  of  Pond  and  Location 


Breed's  pond,  Lynn 

Birch  pond,  Lynn      

Walden  pond,  Saugus 

Hawkes'  pond,  Saugus . 

Spring  pond,  Salem 

Brown's  pond,  Peabody 

Cedar  pond,  Peabody 

Winona  lake  or  Lily  pond,  Peabody      

Bartholomew's  pond,  Peabody 

Suntaug  lake,  Peabody  and  Lynnfield 

Bancroft's  pond,  Peabody 

Fillings'  pond,  Lynnfield      

Forest  lake,  Middleton ;    .    .    . 

Hood's  pond,  Topsfield  and  Ipswich      

Kimball's  pond,  Amesbury  and  Merrimac     .    .    .    . 

Gardner  lake,  Amesbury      , 

Hackett's  pond,  Andover 

Foster's  pond,  Andover 

Pomp's  pond,  Andover 

Low's  Saw-mill  pond,  Boxford 

Crooked  pond,  Boxford 

Stevens'  pond,  Boxford 

Fom- Mile  pond,  Boxford 

SpofEord's  pond,  Boxford 

Stiles'  pond,  Boxford 

Bald  Pate  or  Parley's  pond,  Boxford 

Johnson's  pond,  Boxford  and  Groveland 

Crane  pond,  Groveland 

Lake  Cochichewick  or  Great  pond.  North  Andover 
Lake  Saltonstall  or  Plug  pond,  Haverhill      .    .    .    . 

Kenoza  lake,  Haverhill 

Round  pond,  Haverhill 

Crystal  lake  or  Creek  pond,  Haverhill 

South  or  Youth's  pond,  Methuen 

Mystic  pond,  Methuen      

Stevens'  pond,  Methuen 

Pentucket  pond,  Georgetown       

Rock  pond,  Georgetown       

Chadwick's  pond,  Bradford 


Feet 

Acres 

60 

52 

60 

44 

0  to  100 

variable 

0  to  100 

variable 

60 

30 

60 

25 

80 

i7i 

80 

10 

80 

8i 

100 

i6s 

20 

18 

80 

S9i 

80 

100 

80 

68 

80 

306 

80 

52 

100 

220 

80 

105 

100 

37 

100 

50 

160 

12 

100 

13 

100 

42 

100 

22 

100 

60 

100 

54 

100 

200 

60 

20 

180 

450 

118 

41 

112 

234 

148 

38 

148 

175 

140 

45 

140 

18 

140 

18 

140 

S8 

140 

75 

100 

126 

Appendix  E 

GEOLOGICAL  SUCCESSION  OF  THE  ROCK  FORMATIONS  OF  ESSEX 
COUNTY,  MASSACHUSETTS. 

Archean  or  Pre-Cambrian : 

Arkose,  conglomerate  granite,  hornblende  epidote  gneiss. 

Lower  Cambrian  or  Algonkian: 

Metamorphosed  slates,  sandstones,  conglomerates. 

Paleozoic : 

Cambrian  white  limestones,  chert,  slate  quartzite. 
Blue  limestone,  red  slate,  ferruginous  quartzite. 

Post-Cambrian : 

Plutonic  eruptives. " 

Hornblende  diorite,  amphibolite  gneiss. 

Diallage  gabbro,  dike  rocks  including  serpentine,  peridotites. 

Quartz  augite  hornblende  diorites  with  foliated  forms. 

Hornblende  granite,  aplite  granite  dikes. 

Porphyritic  hornblende  granite  with  gneissic  forms. 

Muscovite  biotite  granite,  foliated  muscovite  biotite  granite. 

Syenite  Series: 

Essexite  group.     Salemite. 
Nepheline  syenite,  pulaskite,  hednunite. 
Augite  syenite  (akerite),  quartz  augite  syenite. 
Quartz  mica  hornblende  syenite  (nordmarkite) . 
^girine  syenite,  arfvedsonite,  quartz  mica  syenite. 

Dike  Rocks  of  the  Syenite  Series: 

Camptonite. 

Acmite,  ffigirine  tinguaite. 

Analcite  tinguaite. 

Solvsbergite  (Bostonite  porphyry). 


APPENDIX  403 

Kersanite. 

Keratophyre  —  a  surface  lava  flow. 

Umptekite  or  hornblende  gabbro  series. 

Ancient  Volcanic  Rocks: 

Aporhyolite  —  massive  igneous  rocks. 

Aporhyolite  agglomerates,  breccias,  foliated  or  banded  aporhyolites. 
Porphyritic  aporhyolite,  felsitic  rhyolite,  quartz  porphyry  aporhyo- 
lite, conglomerate  aporhyolite,  lithophase. 
Aporhyolite  dike  rocks. 
Felsitic  porphyry. 
Quartz  porphyry. 
Liparite. 
Vitrophyre. 

Superficial  Unconsolidated  Rocks: 

Cenozoic  Pleistocene  Era. 

Till  or  ground  moraine,  older  diluvium.  _ 

Glacial  marine  clay  containing  fossils. 
Boulder-till  of  drumlins. 

Terminal  moraines,   eskers,   later  clay-beds  formed  in  ancient  es- 
tuaries. 
Physozoic  Era. 
Post-Terrace  Era. 
Peat-beds,  river  alluvium,  silts. 
Present  Epoch. 

Evidence  of  subsidence,  submerged  forest  trees,  drowned  stream- 
and  river-valleys,  recently  formed  deltas,  sand  beaches  and 
dunes. 


Appendix  F 

CHEMICAL  ANALYSES    OF   THE    ROCKS    OF    ESSEX   COUNTY, 
BY  PROFESSOR   HENRY   S.   WASHINGTON,    OF    LOCUST,  N.  J. 


I 

II 

III 

IV 

V 

VI 

VII 

VIII 

IX 

X 

XI 

XII 

SiO,      

77.61 
0.2s 

77-14 
0.29 

12.24 
0.29 
1.04 
trace 
0.06 
0.3s 

4.64 
4.47 
trace 
0.14 

76.49 
trace 

■"i;.89 

I.I6 
1.56 

trace 
trace 
0.14 

4.03 
5.00 

oji 

73.93 

12.29 
2.91 
1.5s 

trace 
0.04 
0.31 

none 
4.66 
4.63 

0.41 

71.40 

14.76 
1.68 
0.72 
trace 
0.55 

4.79 
S.16 

'"i.;6 

70.64 
0.90 

15-34 
1.83 

trace 
0.52 
1.24 

5-23 
3.5s 
0.14 
0.38 

68.88 
0.19 

14.77 
0.64 
4.64 
trace 
0.37 
1.74 

"3.83 
4.97 
0.06 
0.24 

68.36 

trace 

■16.58 
0.90 
3-24 

trace 
0.45 
1.85 

3.97 
0.17 

67.3s 
0.60 

15.05 
1.23 

4-76 

0.05 
0.03 
0.55 

4.42 
6.08 
0.16 
0.17 

66.60 
0.76 

15.05 
1.07 
4.42 

trace 
0.36 

4.03 
542 

041 

64.28 
0.50 

15.97 
2.91 
3.18 
trace 
0.03 
0.85 

°°7.28 
5-07 

0.08 

63.71 

liO.  

ZrO.     

11.94 

fM 

trace 

trace. 

0.31 

3-80 
4.9S 
trace 
0.23 

18.30 
2.08 

FesO, 

FeO' •.. 

MnO 

2.52 

MgO  

0.09 

l.lS 

CaO 

BaO 

Na.O 

K2O 

6.21 

HjOdio") 

H,0  (ignit) 

P.Os    

0.09 
0.17 

100.54 

100.66 

100.77 

100.91 

100.62 

100.87 

100.33 

100.97 

100.4s 

100.33 

100.33 

100.74 

2.618 
18°  C. 

2.650 
13°  c. 

22=^6^ 

.2^^^. 

'^'A 

2.690 

17°  c. 

2.612 
17°  C. 

2^'C^ 

12°  c. 

TABLE  L— Continued. 


M- 

XIII 

XIV 

XV 

XVI 

XVII 

XVIII 

XIX 

XX 

XXI 

XXII 

XXIII 

XXIV 

SiO. 

63.09 
0.45 
0.06 

18.50 
2.90 
1.36 
trace 
0.16 

7.25 
5.23 

o!62 

61  .OS 

0.34 

'i8.8'i 

3.06 
trace 
0.42 
1.30 

6.56 
6.02 

"0.78 

6001: 

59  31 
0.32 

22.50 
1-93 
1.40 

trace 
0.17 
0.46 

"  '7.98 
4.08 
o-iS 

58.77 
0.31 

22:64 

1-54 
1.04 

trace 
o.ig 
0.74 

none 
g.62 
4.89 
0.07 
0.90 

56.75 
0.30 

20.69 
3-52 
0-59 
trace 

0.37 
none 
11-45 
2.90 
0.04 
3.18 
Cl=o.28 

51.82 

2.IS 

1.97 
8.60 

trace 
4.87 
8.59 

3-44 
1.77 

47.12 
3.27 

14.43 

3-33 
11.71 

6.05 
9.63 

"2.58 

0.28 

0.34 

46.99 
2.92 

17.94 

2.56 
7.56 

7.85 

none 
6.35 
2.62 

■0.6s 
0.94 

46.59 
1.41 

17.55 

1.6S 
10.46 

■  '7.76 
10.64 

3.31 
0.72 

0.07 

45.32 
1.94 

18.99 

3.78 

9.78 

' "  4^68 
9.19 

"378 

0.09 
0.31 

TiO'z    

19 

4 

97 
32 
04 
79 
23 
91 

ZrO, 

AI2O3  .... 

Fe,0, 

FeO    

MnO 

MgO  . 

4.32 

6.93 

CaO 

BaO 

NajO 

7 
3 

Cl=o 

69 
24 

28 

ICO 

HoOdio") 

H2O  (ignit) 

PjOb 

0.08 
0.15 

100.83 

100.36 

100.04 

99.42 

100.S2 

100.18 

100.58 

99.85 

9Q.60 

100.29 

99.98 

99.40 

Sp.  Gr.. 

2.655 
12°  C. 

2.708 

I2™C. 

ii™C. 

2.474 
22°  C. 

3.072 

2.919 
12°  C. 

3.047 
11°  c. 

V?^'L 

3-058 

ti°C. 

Granite.     Rockport. 

Aplite  (mean).     Bass  Rocks. 

Paisanite .    Magnolia . 

Granite.     Quincy.     (Blue  hills.) 

Keratophyre.     Marbleliead  Neck. 

Rhyolite.     Marblehead  Neck. 

Quartz  syenite  porphvrv.     Squam  light. 

Nordmarkite.     Wolf  hill. 

Enclosure  in  Granite.     Rockport. 

Akerite.     Gloucester. 

Solvsbergite.     Andrews'  point. 

Pulaskite.     Salem  Neck. 


XIII. 

Pulaskite.     Salem  Neck. 

XIV. 

Solvsbergite.     Coney  island. 

XV. 

Tinguaite.     Gale's  point.     (Eakle.) 

XVI. 

Foyaite.    Great  Haste  ledge. 

XVII. 

Foyaite.     Salem  Neck. 

XVIII. 

Tinguaite.     Pickard's  point. 

XIX. 

Diorite.    Marblehead. 

XX. 

Diabase.     Rockport. 

XXI. 

Essexite.     Salem  Neck. 

XXII. 

Camptonite.     Salem  Neck. 

XXIII. 

Hornblende  Gabbro.     Salem  Neck. 

XXIV. 

Gabbro.     Nahant. 

QUANTITATIVE    CLASSIFICATIONS    OF     THE    ANALYSES    OF    THE 
ROCKS   OF   ESSEX   COUNTY. 

By  Professor  Henry  S    Washington. 


In  the  following  table ,  the  rocks'^of  Essex  Coionty  are  classified  accord- 
ing to  the  chemical  analyses  of  igneous  rocks  arranged  by  Dr.  Henry  S. 
Washington,  in  Professional  Paper  No.  14,  published  in  1903,  by  the 
United  States  Geological  Survey. 


Class  I,  order  4,  rang  i,  subrang  3,  Liperose. 

Hornblende  granite,  Rockport. 

Paisanite,  Magnolia. 

Quartz  syenite,  Pigeon  Hill  quarry,  Rockport. 

Aplite,  Bass  rocks,  East  Gloucester. 

Keratophyre,  Marblehead  Neck. 

Keratophyre,  Marblehead  Neck,  Boden's  point. 

Class  I,  order  4,  rang  2,  subrang  3   Toscanose. 

Quartz  syenite  porphyry,  near  Squam  light.  Cape  Ann. 
Nordmarkite,  Wolf  Hill,  Gloucester. 
Akerite,  Gloucester. 

Class  I,  order  5,  rang  i,  subrang  4,  Phlegrose. 

Hedrumitic  pulaskite,  Salem  Neck. 

Class  I,  order  5,  rang  i,  subrang  4,  Nordmarkose. 

Pulaskite,  Salem  Neck. 

Solvsbergite  syenite  porphyry,  Coney  island,  Salem  harbor. 

Biotite  tinguaite,  Gale's  point,  Manchester. 

Foyaite,  Great  Haste  ledge,  Salem  harbor. 

Class  I,  order  6,  rang  i,  subrang  4,  Miaskose. 

Foyaite,  Salem  Neck. 

Analcite  tinguaite,  Pickard's  point,  Manchester. 

Class  II,  order  5,  rang  i,  subrang  4,  Umptekose. 

Glaucophane-solvsbergite,  Andrews'  point,  Cape  Ann. 

Class  II,  order  5,  rang  3,  subrang  4,  Andose. 

Diorite,  Peach's  point,  Marblehead. 

Class  II,  order  5,  rang  4,  subrang  3,  Hessose. 

Gabbro,  Nahant. 

Class  II,  order  6,  rang  2,  subrang  4,  Essexose. 

Essexite,  Salem  Neck. 

Class  II,  order  6,  rang  3,  subrang  4,  Salemose. 

Hornblende  gabbro,  Salem  Neck. 

Class  III,  order  5,  rang  3,  subrang  4,  Camptonose. 

Diabase,  Rockport. 

Class  III,  order  5,  rang  4,  subrang  3,  Auvergnose. 

Camptonite,  Salem  Neck. 


Appendix  G 

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APPENDIX  409 

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INDEX 


Acmite,  238. 

Actinolite,  238, 

Actinolitic  quartz,  237. 

JEgirine,  238. 

^girine  tinguaite,  209.         , 

Agassiz  boulder,  344. 

Ainigmatite,  238. 

Akerite,  178,  igo. 

Albite,  245. 

Albite  and  ortlioclase  intergrowths,  245. 

Alkali  hornblende,  238. 

AUanite,  241. 

Almandite  garnet,  241. 

Amazon  stone,  245. 

Amesbury,  167,  266,  302. 

Analcite  tinguaite,  209. 

Andalusite,  246. 

Andover,  98,   149,   168,   170,   173,  271,  272 

307- 
Ankerite,  249. 
Ann,  Cape,  328. 
Annite,  242. 
Anorthite,  245. 
Anorthoclase,  245. 
Antimony,  Gray,  233. 
Apatite,  249. 

Aporhyolite,  214,  236,  240,  244. 
Areas  of  land  and  water,  393. 
Arfvedsonite,  238. 
Arkose,  97,  106,  254. 
Arsenopyrite,  233, 
Artesian  well,  83. 
Asbestos,  133. 
Asbestus,  238. 
Asteracanthion,  369. 
Astrophyllite,  241. 
Augite,  237, 
Augite,  Brown,  238. 
Augite  hornblende  gabbro,  173. 
Augite  syenite,  42,  178,  194. 
Ayer's  Village,  171. 
Azurite,  249. 


Baker's  island,  146. 

Bald  hill,  Beverly,  193. 

Bald  Pate  hill,  Georgetown,  314. 

Ballardvale,  22. 

Baltimorite,  246. 

Bars,  45. 

Bars  of  sand,  62,  66. 

Basanite,  237. 

Bastite,  246. 

Bays,  45. 

Beaches,  58,  64,  66,  70.  82,  295,  318. 

Beaches,  Inland,  272. 

Beacon  ledge,  67. 

Beaver  brook,  28. 

Beaver  pond,  Beverly,  265. 

Bed-rock  outcrops,  76,  399. 

Beverly,  22,  51,  60,  153,  174,  190,  201,  265, 

268,  276,  280,  327,  328,  358,  374. 
Bibliography,  406. 
Biotite  mica,  241. 
Biotite  tinguaite,  205. 
Black  brook,  28. 
Boden's  rock,  57. 
Bog-butter,  250. 
Bog  iron,  234. 
Bog  manganese,  234. 
Bogs,  Quaking,  284. 
Bomite,  233. 
Boston  brook,  28. 
Bostonite  porphyry,  202. 
Boulder- till,  277. 
Boulders,    78,   113,  120,  124,  128,   137,  156, 

320;  326,  328,  330,  334,  336,  343,  344. 
Bowditch's  ledge,  57. 

Boxford,  88,  90,  109,  132,  136,  284,  308,  314. 
Bradford,  loi. 
Breakheart  hill,  Saugus,  76. 
Brick  making,  357. 
Bronze  siderite,  249. 
Bronzite,  238. 
Brown  hematite,  234. 
Brown  ochre,  234. 


413 


414 


Bnicite,  234. 
Bull  brook,  28. 
Byfield,  166,  271, 


295- 


Cairngorm  stone,  237. 

Calc  spar,  249. 

Calcite,  249. 

Cambrian  rocks,  33,  34,   83,   106,  178,  182, 

186,  229,  380. 
Canal,  Early,  335. 
Cancrinite,  245. 
Castle  hill,  Salem,  108. 
Castle  neck,  Ipswich,  62,  72,  78. 
Castle  river,  80. 
Cat  island,  229. 
Cedar,  Red,  39. 

Chain  bridge,  Newbur5rport,  96,  125. 
Chalcedony,  237. 
Chalcopyrites,  233. 
Chalybeate  springs,  22. 
Champlain  subsidence,  272. 
Chemical  analysis  of  Essex  County  rocks, 

404. 
Chert,  237. 

Chestnut  trees  at  Danvers,  36. 
Chiastolite,  246. 
Chromic  iron,  234. 
Chromite,  234. 
Chrysolite,  238. 
Chrysotile,  246. 
Cinnamon  stone,  241. 
Clark's  pond,  Ipswich,  75. 
Clay,  357. 

Clay  iron  stone,  234. 
Cliffs,  45. 
Coal,  250. 
Coast-lines,  45. 
Cobble-stones,  374. 

Coffin's  beach,  Gloucester,  67,  70,  72,  80. 
Coke,  34. 

Compass,  Magnetic,  7. 
Coney  island,  202. 
Copper,  Blue  carbonate  of,  249. 
Copper,  Gray,  233. 
Copper,  Green  carbonate  of,  249. 
Copper  ore,  233. 
Cossyrite,  238. 
Cradle  rock,  124. 
Crane  river,  54. 

Crooked  pond,  Boxford,  284,  306. 
Cryophyllite,  242. 


Crystal,  Rock,  237. 
Currents,  62. 

Danalite,  238. 

Danvers,  21,  36,  54,  145,  153,  265,  320,  356, 

357.  363.  378,  382. 
Deer  Leap  rocks,  173. 
Delessite,  246. 

Devil's  den,  Newbury,  116,  133. 
Diallage,  237. 
Dike  rocks,  go,  98,  142,  154,  164,  168,  171, 

173,  180,  192,  198,  206,  209,  226,  402. 
Diopside,  238. 

Diorite,  39,  90,  125,  129,  137,  145,  178,  182. 
Divides,  21. 
Dogtooth  spar,  249. 
Dogtown  Common,  336. 
Dolomite,  249. 

Drainage  and  valley  systems,  27. 
Drainage  creases,  290,  316. 
Drift  materials,  46,  58. 
Drift-sand,  61,  74. 
Drowned  river  valleys,  46. 
Drumlins,  277,  395. 
Drumlins  carved  by  landslides,  344. 
Drumlins,  elevations  and  location,  395. 
Drusy  quartz,  237. 
Dungeons,  Marblehead,  284,  298,  300,  304. 

Eagle  hill,  Ipswich,  288. 

Earth,  Infusorial,  237. 

Elasolite,  245. 

Elevation  of  surface,  253,  373. 

Enstatite,  238. 

Epidote,  241. 

Erosion,  45,  46,  58,  61,  68,  373. 

Erratic  boulders,  320,  328,  343. 

Eruptive  plutonic  rocks,  125. 

Eruptive  rocks,  32,  171,  177,  222. 

Eskers,  259. 

Essex,  80,  97,  IS4,  156,  316,  343,  352. 

Essex  County,  area,  21,  252. 

Essex  County  land  areas,  393. 

Essex  County,  settlement  of,  27. 

Essex  river,  28. 

Essexite,  177,  181,  184,  185. 

False  topaz,  237. 
Fayalite,  161,  238. 
Federal  city,  Groveland,  93. 
Fergusonite,  246. 


INDEX 


415 


Ferruginous  gravel,  324. 
Ferruginous  quartz,  237. 
Fibrolite,  246. 
Fish,  brook,  Boxford,  28. 
Fluorite,  234. 
Fluor-spar,  234. 
Foliated  quartz  diorites,  137. 
Forest  lake,  Middleton,  314. 
Forest  river,  56. 

Fossils,  34,  52,  84,  98,  105,   122,  272,  363, 
376-391- 

Gabbro,  Augite  hornblende,  173. 

Gabbro,  Labradorite,  198. 

Gabbro,  Umptekite,  210. 

Galena,  233. 

Gale's  point,  Manchester,  70. 

Gap  head,  Rockport,  42. 

Garnet,  171,  238. 

Garnet,  Almandite,  241. 

Garnet,  Grossularite,  241. 

Geological  distribution  of  plants,  34. 

Geological  succession  of  rock  formations,  402, 

Georgetown,  22,  no,  254,  289,  308. 

Glacial  drift  boulders,  78. 

Glacial  ice,  253,  259,  264,  277,  373. 

Glacial  scratches,   136,   254,   256,   258,   278, 

301,  322,  328,  343. 
Glaucophane,  238. 
Gloucester,  38,  67,  68,  70,  72,  80,  94,  148, 

156.  157,  161,  194,  201,  332,  334,  335. 
Granite,  Micrographic,  154. 
Granite,  Muscovite  biotite,  168. 
Gneiss,  90,  170. 
Gold,  230. 

Gooseberry  island,  229. 
Granophyre,  154. 
Graphite,  233. 
Grasshopper  plain,  Newburyport,  266,  277, 

296. 
Gravel,  277,  295,  324,  372. 
Graves'  island,  75,  162. 
Great  spring,  Danvers,  22. 
Grossularite  garnet,  241. 
Groveland,  93,  112,  120,  129,  260,  308. 
Guano,  249. 

Halite,  233. 

Hamilton,  260,  270,  274,  352. 
Haverhill,  171,  173,  292,  294,  298,  313,  324, 
356.  358- 


Haystack  boulder,  128. 

Headlands,  45. 

Hematite,  234. 

Hematite,  Brown,  234. 

Hematite,  Micaceous,  234. 

Hills  (bed-rock)  in  Essex  County,  399. 

Hills  (drumlins)  in  Essex  County,  395. 

Hog  island,  Essex,  286,  292,  350. 

Hornblende,  23S. 

Hornblende,  Alkali,  238. 

Hornblende  diorite,  129. 

Hornblende  epidote  gneiss,  88,  go. 

Hornblende  gabbro,  177. 

Hornblende  granite,  38,  39,  42,  88,  150. 

Hydrocarbon,  Oxygenated,  250. 

Hydronephelite,  245. 

Hyolithes,  34,  83,  98,  105,  122,  380. 

Hypersthene,  237. 

Ice-block  holes ,  283,  306,  310,  327. 

Ice-contact,  259. 

Ice-sheet,  84,  90. 

Igneous  volcanic  rocks,  222. 

Ilmenite,  234. 

Indian  ridge,  271. 

Infusorial  earth,  237. 

Inland  beaches,  295,  318. 

lolite,  241. 

Ipswich,  44,  61,  72,   78,  154,  288,  294,  296, 

35°.  358- 
Ipswich  beach,  61,  66. 
Ipswich  river,  27,  30,  252,  319. 
Iron,  234. 
Iron,  Bog,  234. 
Iron,  Chromic,  234. 
Iron  pyrites,  233. 
Iron,  Spathic,  249. 
Iron,  Speciilar,  234. 
Iron  stone.  Clay,  234. 
Iron,  Titanic,  234. 

Jackman  farm,  Ipswich,  62. 
Jaspelite,  237. 
Jeffersite,  246. 
Jeffrey's  ledge,  S3,  386. 
Jeffrey's  Neck,  Ipswich,  44. 
Jeggles'  island,  Salem,  56. 

Karnes,  283,  312. 
Kaolin,  225,  357- 


416 


Kaolinite,  246. 

Kent's  island,  Newbury,  225,  301. 
Keratophyre,  214. 
Kettle-holos,  259,  283,  290,  301. 
Knottinschieflfer,  76,  113. 

Labradorite,  245. 

Labradorite  gabbro,  198. 

Lakeman  farm,  Ipswich,  67,  74. 

Lakes  and  ponds  in  Essex  County,  400. 

Landslides,  344. 

Lawrence,  20,  26,  96,  97,  164,  168,  170,  307. 

Lead,  233. 

Leda  clay,  357,  363. 

Ledge  Hill  park,  Salem,  254,  258. 

Ledges,  34,  332. 

Legg's  hill,  Salem,  283,  300,  372. 

Lepedomelane,  241. 

Lepidolite,  241. 

Leucoxene,  234. 

Lime,  Phosphate  of,  249. 

Limestone,  38,  39,  45,  84,  121,  133,  249,  380. 

Limestone,  Magnesian,  249. 

Limonite,  234. 

Lithia  mica,  241. 

Lithia  springs,  22. 

Longham  basin,  Beverly,  372. 

Lowell  island,  229. 

Lynn,  51,  165,  190,  225,  327. 

L5mnfield,  no,  142,  178,  190,  319,  384. 

Magnesian  limestone,  249. 

Magnesite,  249. 

Magnetite,  234. 

Malachite,  249. 

Manchester,   51,  68,   70,   75,   152,   161,   192, 

205,  343. 
Manganese,  Bog,  234. 
Marble,  249. 
Marblehead,  75,  82,  146,  162,  166,  214,  222, 

226,  258,  283,  300. 
Marblehead  harbor,  _  7 . 
Marcasite,  233. 
Marmolite,  246. 
Marshes,  42,  44,  45. 
Menaccanite,  234. 
Merrimac,  loi,  266. 
Merrimac  river,   20,  24,   27,  46,   51,  58,  96, 

308,  324,  326. 
Metamorphism,  76,  171,  181. 


Metcalf's  rock,  130. 

Methuen,  98,  271,  302. 

Mica,  Biotite,  241. 

Mica-granite,  172. 

Mica,  Lithia,  241. 

Mica,  Muscovite,  241. 

Mica,  Phlogopite,  241. 

Mica-schist,  38,  39,  45,  76,  94,  97  (2). 

Micaceous  hematite,  234. 

Microcline,  245. 

Microcline  microperthite,  245. 

Micrographic  granite,  154. 

Middleton,  30,  138,  141,  154,  314. 

Miles  river,  28. 

Milky  quartz,  237. 

Mill  creek,  28. 

Mineral  waters,  22. 

Minerals  of  Essex  County,  230,  248. 

Mingo  beach,  Beverly,  60. 

Mining,  225. 

Misery  island,  Salem,  190. 

Mispickle,  233. 

Mitchell's  falls,  Merrimac  river,  24. 

Molybdenite,  233. 

Monadnocks,  34. 

Moraines,  259,  307,  336. 

Moses'  mountain,  154,  344. 

Mosquito  brook,  28. 

Mount  Desert,  253. 

Mount  Greylock,  253. 

Muscovite  biotite  granite,  168. 

Muscovite  biotite  granite,  foliated,  168. 

Muscovite  mica,  241. 

Nahant,  38,  45,  51,  60,  104,  114,  121,  380, 

386,  39°- 
Natrolite,  245. 
Nepheline,  245. 
Nepheline  syenite,  i8g,  192. 
Nephelite,  245. 
Newbury,  106,  116,  126,  128,  130,  132,  225, 

278,  288,  295,  301,  322. 
Newburyport,  96,  266,  277,  296,  358. 
Nichols'  brook,  Dan  vers,  28. 
Nickel,  173,  233. 
Niles'  pond,  Gloucester,  334. 
Noble  serpentine,  246. 
Nordmarkite,  201. 
Norseman's  rock,  124. 
Norwood's  pond,  Beverly,  265. 
Nubble  squid,  Groveland,  112,  129,  134. 


417 


Ochre,  Brown,  234. 

Ochre,  Red,  234. 

Ochre,  Yellow,  234. 

Olivin,  238. 

Opal,  237. 

Ordway  boulder,  128. 

Orthite,  241. 

Orthoclase,  245. 

Orthoclase  microperthite,  245. 

Orthoclase,  Pseudomorph  of,  246. 

Outcrops  of  bed-rock,  76. 

Paisanite,  173. 

Paleontology  of  Cambrian  rocks,  380. 

Parker  river,  28,  46,  48. 

Peabody,  142,  165,  320,  330. 

Peabody  Academy  of  Science,  230,  248. 

Peat,  283. 

Peat  deposits,  34,  51. 

Pennenite,  246. 

Petricola,  52. 

Phlogophite  mica,  241. 

Picrolite,  246. 

Picrosmine,  246. 

Pine  swamp,  Ipswich,  289,  295. 

Pinite,  246. 

Plants,  Geological  distribution  of,  34. 

Plum  island,  46,  58,  62. 

Plutonic  rocks,  Eruptive,  125. 

Pond  beach,  Nahant,  60. 

Ponds  and  lakes  in  Essex  County,  400. 

Porphyritic  granite,  166. 

Porphyry,  202,  225. 

Portlandia  Arctica,  363,  370,  373,  376. 

Post-Cambrian  rocks,  402. 

Post-Pleistocene  sand  and  gravel,  295. 

Potteries,  358. 

Powow  river,  27. 

Prase,  237. 

Prehnite,  245. 

Privy  ledge,  57. 

Pulaskite,  201. 

Pulaskite  syenite,  180,  200. 

Pyrite,  233. 

Pyrites,  Copper,  233. 

Pyrites,  Iron,  233. 

Pyrites,  White  iron,  233. 

Pyroxene,  237. 

Pyrrhotite,  233. 

Quaking  bogs,  284. 

Quantitative  classifications  of  the  rocks,  405. 


Quartz,  237,  249. 

Quartz,  Actinolitic,  237. 

Quartz  augite  diorite,  125. 

Quartz  augite  syenite,  190. 

Quartz  diorite,  go,  125. 

Quartz,  Drusy,  237. 

Quartz,  Ferruginous,  237. 

Quartz  hornblende  diorite,  92. 

Quartz,  Milky,  237. 

Quartz,  Rose,  237. 

Quartz,  Smoky,  237. 

Quartzite,  237. 

Quatenary  Pleistocene  period,  253. 

Rabbit  rock,  149. 

Raccoon  rocks,  152,  344. 

Residua! clays,  357. 

Rhyolite,  76. 

River  systems,  27. 

Roches  Moutonnees,  254,  262. 

Rock  crystal,  237. 

Rockport,  148,  150,  157,  161,  256,  335. 

Rose  quartz,  237. 

Rowley,  44,  84,  93,  122,  130,  222,  271,  286, 

352,  384- 
Ruby  spinel,  249. 
Rutile,  234. 
Ryefield,  Byfield,  295. 

Salem,  56,  83,  86,   108,  136,  142,  146,   178, 

180,  192,  254,  258,  278. 
Salem  harbor,  57. 
Salemite,  186. 
Salisbury,  302. 
Salisbury  beach,  58. 
Salt,  233. 
Sanadin,  245. 
Sand,  58,  62,  271,  295. 
Sand-bars,  62,  66. 
Sand-dunes,  62,  295. 
Sand-ridges,  61. 
Sandstone,  76,  117. 
Sandy  bay,  Rockport,  68. 
Saugus,  113,  166,  232,  328. 
Saugus  rive'r,  50. 
Scapolite,  241. 
Schiefferhornfels,  97. 
Schiller  spar,  246. 
Sedimentary  rocks,  32,  76,  94. 
Sedin:ient  58,  84. 
Sericite,  241. 


418 


INDEX 


Serpentine,  133,  246. 

Serpentine,  Noble,  246. 

Shale,  121. 

Shawsheen  river,  27. 

Sheep  backs,  254,  262. 

Ship  rock,  Peabody,  320,  326. 

Siderite,  249. 

Siderite,  Bronze,  249. 

Silicious  sinter,  237. 

Silver,  233. 

Singing  Sand  beach,  Manchester,  68. 

Sinter,  Silicious,  237. 

Slate  or  mica-schist,  38,  39,  45.  7^,  97- 

Smoky  quartz,  237. 

Soapstone,  245. 

Soda-microcline,  198,  245. 

Sodalite,  245. 

Solvsbergite,  202. 

Soundings,  57. 

Spar,  Brown,  249. 

Spar,  Calc,  249. 

Spar,  Dogtooth,  249. 

Spar,  Schiller,  246. 

Spar,  Tabular,  237. 

Spathic  iron,  249. 

Specular  iron,  234. 

Sphalerite,  233. 

Sphene,  246. 

Spicket  river,  Lawrence,  26,  27,  302. 

Spinel,  Ruby,  249. 

Split  boulder,  120. 

Springs,  22. 

Squam  river,  42,  335. 

Steatite,  245. 

Stenotheca,  83,  106. 

Stibnite,  233. 

Stickney  boulder,  120,  134. 

Stone,  Amazon,  245. 

Stone,  Cairngorm,  237. 

Stone,  Cinnamon,  241. 

Straitsmouth  island,  Rockport,  42. 

Stratified  rocks,  76. 

Subsidence,  46,  51,  272,  292,  370. 

Sugar  loaf  hills,  106,  254,  262. 

Surface  areas,  393. 

Surface  features,  34. 

Syenite,  Augite,  42,  178,  194. 

Syenite,  Nepheline,  189,  192. 

Syenite,  Pulaskite,  180,  200. 

Syenite  rocks,  177,  402. 

Syenites  of  Salem  Neck,  178,  184. 


Talc,  246. 

Tertiary  uplift,  253,  373. 
Tetrahedrite ,  233. 
Thatcher's  island,  198,  229. 
Thompson's  mountain,  158. 
Tilting  of  the  surface,  33,  373. 
Tinguaite,  JEgirine,  209. 
Tinguaite,  Analcite,  209. 
Tinguaite  dike,  206. 
Titanic  iron,  234. 
Titanite,  246. 
Toadstone,  225. 
Tombolas,  75,  265. 
Topaz,  False,  237. 

Topsfield,   22,   84,   106,   118,   154,  252,   254, 
260,  262,  290,  296,  314,  352,  384,  388,  390. 
Tourmaline,  246. 
Tremolite,  238. 
Tripolite,  237. 
Turgite,  234. 

Umptekite,  177. 
Umptekite  gabbro,  210. 
Upper  clays,  357. 
Uralite,  246. 

Valley  systems,  formations  of,  27. 
Vesuvianite,  134,  241. 
Volcanic  rocks,  32,  222,  403. 

Wad,  234. 

Wash-plains,  278. 

Waters'  river,  54. 

Watersheds,  21. 

Wenham,  265,  276,  310. 

Wenham  lake,  316. 

Wenham  swamp,  34,  284. 

Wernerite,  241. 

West    Newbury,    loi,    105,    166,    266,    313, 

346,  348- 
Willowdale,  260,  274. 
Winds,  Effect  of,  66. 
Winter  island,  178,  181. 
Wolf  hill,  Gloucester,  342. 
WoUastonite,  237. 

Xanthosiderite,  234. 

Yttrocerite,  250. 

Zinc  blende,  233. 
Zircon,  238. 
I    Zoisite,  241. 


-DX 


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i.BBi;j^  x:Dum'r/i>j_A\£;£;, 


BY  JOHN  H.  SSIMS. 


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PUBLISHED  BV  THE  ESSEX  INSTITUTE,  SAUM.  MASS\CHUSETTS. 

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DATE  DUE 

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2003 

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UNIVERSITY  PRODUCTS,  INC.    #859-5503 

BOSTON  COLLEGE 


3  9031    027  49758  5 


